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Article

Synthesis of New Zinc and Copper Coordination Polymers Derived from Bis (Triazole) Ligands

by
Maria Cristina Al-Matarneh
1,*,
Alina Nicolescu
2,*,
Ioan-Andrei Dascalu
1,
Sergiu Shova
3,
Cristian-Dragos Varganici
1,
Adrian Fifere
1,
Ramona Danac
4 and
Ioana-Cristina Marinas
5
1
Center of Advanced Research in Bionanoconjugates and Biopolymers, “Petru Poni” Institute of Macromolecular Chemistry of Romanian Academy, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
2
NMR Laboratory, “Petru Poni” Institute of Macromolecular Chemistry of Romanian Academy, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
3
Department of Inorganic Polymers, “Petru Poni” Institute of Macromolecular Chemistry of Romanian Academy, 41A Grigore Ghica Voda Alley, 700487 Iasi, Romania
4
Faculty of Chemistry, Alexandru Ioan Cuza University of Iasi, 11 Carol I Bvd., 700506 Iasi, Romania
5
Research and Development Department, SC Sanimed International Impex SRL, 6 Bucharest-Giurgiu Street, 087040 Giurgiu, Romania
*
Authors to whom correspondence should be addressed.
Crystals 2024, 14(2), 144; https://doi.org/10.3390/cryst14020144
Submission received: 19 December 2023 / Revised: 27 January 2024 / Accepted: 29 January 2024 / Published: 30 January 2024
(This article belongs to the Special Issue Feature Papers in Crystals 2023)
Browse Figures
Versions Notes

Abstract

:
Recent research has focused on molecules with different aromatic nitrogen-containing moieties coupled to a biphenyl core, as an effective approach for the assembly of coordination polymers. This study presents the synthesis and characterization of new ligands based on 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-butyl-1H-1,2,3-triazole) (L1) and 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-phenyl-1H-1,2,3-triazole) (L2) and their coordination polymers with Cu(II) and Zn(II). An unexpected coordination polymer with Cu(I) starting from Cu(II) was obtained in the case of the L2 ligand. The ligands and metal complexes underwent thorough characterization, including X-ray diffraction, NMR-, FTIR-, MS-spectrometry, and EPR, XPS, and TG-DTG analyses. While the ligand L2 generated a linear Cu(I) polymer, the ligand L1 formed a zigzag polymer with both copper and zinc.

1. Introduction

Coordination polymers with chain (one-dimensional) or framework (two- or three- dimensional) structures have drawn a lot of attention in recent years, especially for the development of metal–organic frameworks (MOFs). Generally known as hybrid organic–inorganic compounds formed by coordination bonds and weak intermolecular forces, with intriguing structural topologies, these coordination materials have proven their utility in gas adsorption [1], chemical separations [2], catalysis [3], magnetism [4], microelectronics [5], luminescence [6], and other research areas [7,8].
As there are numerous coordination polymers reported in the literature, it is now widely accepted that the self-assembly process depends on a number of experimental parameters, including the class of organic ligands [9], geometric requirements of metal ions [10], and reaction conditions such as solvent [11], temperature [12], stoichiometry [10], or pH. The type of organic ligand is one of the principal elements in the construction of coordination polymers with predictable architectures. In addition to “common” multitopic carboxylate ligands, polynitrogen heterocycles are a promising family of ligands for the synthesis of these coordination derivatives. Because polynitrogen ligands have multi-coordination sites, they thus a wide range of potential coordination modes with the metal ions, so it is feasible to create crystals with a variety of pores and channels that can generate interesting physicochemical and/or biological features [13]. Known to act as dinucleating or trinucleating ligands, substituted 1,2,3-triazole derivatives are a significant class of N-donors commonly utilized in the assembly of coordination polymers, mainly due to their outstanding coordination capabilities and high versatility [12,14,15,16]. These five-member heterocyclic derivatives, with three nitrogen atoms, are currently prepared by copper(I)-catalyzed azide-alkyne 1,3-cycloadditions (CuAACs), commonly known as “click reactions”. Due to the mild reaction conditions, improved yield and regioselectivity, “click reactions” have been widely exploited to develop a plethora of novel N-heterocycle ligands for increasingly elaborate transition metal coordination polymers [17,18]. Acting as both a metal chelator and C-H hydrogen bond donor, triazole derivatives are recommended for metal-based catalysts [19].
Recent research has focused on molecules with different aromatic nitrogen-containing moieties coupled to a biphenyl core, as an effective approach for the construction of coordination polymers. Compounds possessing a biphenyl ring have attracted a lot of interest from synthetic chemists due to their potential biological activities, several drugs containing this scaffold being used for the treatment of Hepatitis C, hypertension, or even some types of carcinomas [20].
As a continuation of our interest in the field of N-heterocycles (synthesis and properties of novel compounds containing nitrogen [21,22,23] and fast and facile synthesis herein we present the synthesis and characterization of two new linkers, namely 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-butyl-1H-1,2,3-triazole) and 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-phenyl-1H-1,2,3-triazole), as well as the preparation of their coordination polymers with Cu(II) and Zn(II).

2. Materials and Methods

The reagents and solvents that were purchased commercially were used without supplementary purification.

2.1. Characterization Techniques

The melting points were determined using an A. KrüssOptronic Melting Point Meter KSPI (Krüss Optronic GmbH, Hamburg, Germany), without any corrections. For analytical thin-layer chromatography, silica gel plates 60 F254 (Merck Darmstadt, Darmstadt, Germany) were employed, and the visualization was performed using UV light at λmax = 254 or 365 nm. Analyses indicated by the symbols of the elements or functions were within ±0.4% of the theoretical values.
The NMR analysis was performed on Bruker Avance NEO 400 and 600 MHz spectrometers (Bruker Biospin, Ettlingen, Germany). A 5 mm four-nuclei direct detection z-gradient probe (H,C,F,Si-QNP) was used for the 400 MHz spectrometer, while a 5 mm inverse detection multinuclear z-gradient probe was utilized for the 600 MHz spectrometer. The chemical shifts of protons and carbons are expressed in δ units (ppm) relative to the signals of residual solvents. For various experiments like H,H-COSY, H,H-NOESY, H,C-HSQC, and H,C-HMBC, standard pulse sequences provided by Bruker with TopSpin 4.0.8 spectrometer control and processing software were employed. The 15N chemical shifts were derived from the 2D H,N-HMBC spectra and were referenced to external liquid ammonia (0.0 ppm), with nitromethane (380.2 ppm) serving as the external standard.
In the spectral range of 400–4000 cm−1, IR spectra were acquired at room temperature using a Bruker Vertex 70 FT-IR instrument (Shimadzu U.S.A. Manufacturing, Inc., Canby, Oregon, USA) in transmission mode. A resolution of 2 cm−1 and a total of 32 scans were employed for the measurements. The signals intensities in the infrared spectra are described as intense (i), medium (m), and weak (w).
Mass spectra were recorded on a Bruker RapifleX MALDI-TOF/TOF instrument (Bruker Daltonics, Bremen, Germany) equipped with a Smartbeam 3D laser. The instrument was controlled and the MS spectra were processed using Bruker FlexControl Version 4.0 and FlexAnalysis Version 4.0 software.
For MALDI-MS analysis, small amounts from each compound were dissolved in DMSO and diluted by a factor of 10 with methanol. The MALDI matrix solutions were obtained by dissolving 20 mg of α-cyano-4-hydroxycinnamic acid (HCCA) in 1 mL of methanol. Different ratios of the MALDI matrix solution and sample solution (1:1, 2:1, and 4:1) were mixed together, and 1 µL of each resulting solution was deposited onto the MALDI target and dried at room temperature. Mass calibration of the MALDI-TOF/TOF-MS was obtained on Bruker’s peptide mixture standard solution.
The measurements were conducted in positive ion polarity, using reflector mode with a mass scan range of m/z 100–1600 Da. A digitizer with a frequency of 1.25 GHz, a detector voltage of 2117 V, and 1000 shots per pixel were used. The laser power was set between 60% and 80% of the maximum, and 1000 laser shots were accumulated for each spectrum. The laser frequency was set at 5 kHz.
A Rigaku Oxford-Diffraction XCALIBUR E CCD diffractometer (Rigaku, Neu-Isenburg, Germany) with graphite-monochromated MoKα radiation was used for X-ray diffraction measurements. The single crystals were positioned at a distance of 40 mm from the detector. For data collection, a total of 240, 298, 217, 179, and 536 frames were measured, each for 30, 30, 30, 15, and 6 s, respectively, with a 1° scan width. These measurements were performed to obtain data for 3787, 4664, 3944, 3781, and 4684 reflections. The CrysAlis package (Rigaku, Wroclaw, Poland) of Oxford Diffraction [24] was used for unit cell determination and data integration. Absorption correction was applied using the Scale3 Abspack multi-scan method. The structures were solved using the Intrinsic Phasing method and the SHELXT structure solution program implemented in Olex2 software (OlexSys Ltd., Durham, England) [25]. The refinement of the structures was performed using full-matrix least-squares on F2 with SHELXL-2015 [26]. An anisotropic model was used for non-hydrogen atoms. Hydrogen atoms were placed in idealized positions (dCH = 0.96 Å) using the riding model, with their isotropic displacement parameters fixed at 120% of their riding atoms. Tools such as PART, DFIX, and SADI from SHELXL were employed for refining the positional parameters of disordered atoms. A combined anisotropic/isotropic refinement approach was employed for non-hydrogen atoms. Molecular plots were generated using the Olex2 program. The crystallographic data and refinement details are presented in Table 1, while bond lengths and angles are summarized in Table S1 (Supplementary Materials). CCDC-2265351-2265355 contain the supplementary crystallographic data for this contribution. These data can be obtained free of charge via www.ccdc.cam.ac.uk, accessed on 19 December 2023 (or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44)-1223-336-033; or [email protected]).
A Rigaku Miniflex 600 diffractometer (Rigaku, Tokyo, Japan) with CuKα-emission was used to perform the powder X-ray diffraction analysis. The analysis covered an angular range of 2–90° (2θ) with a scanning step size of 0.01° and a recording rate of 2°/min.
Thermogravimetric analysis (TGA) was performed using a STA 449F1 Jupiter equipment manufactured by Netzsch, Selb, Germany. The measurements were carried out within a temperature range of 30–700 °C under a nitrogen flow rate of 50 mL/min, with a heating rate of 10 °C/min. Approximately 10 mg of each sample was heated in alumina crucibles.
For EPR (Electron Paramagnetic Resonance) analysis, 10 mg/mL of [CuL1(NO3)2]n sample was dissolved in DMSO at room temperature. The prepared solution was injected into a quartz capillary tube with a volume of 100 μL and an internal diameter of 1 mm. The sample was then inserted into a standard rectangular cavity of an EMX X-band EPR spectrometer manufactured by Bruker, Ettlingen, Germany. The EPR spectrum was recorded at room temperature (22 °C) using the following parameters: center field 3214 G, sweep width 2000 G, receiver gain 40 dB, modulation amplitude 4 G, attenuation 15 dB (6.325 mW), and a constant time of 40.96 ms.
XPS (X-ray Photoelectron Spectroscopy) spectra were obtained using Axis NOVA equipment from Kratos Analytical, based in Manchester, United Kingdom. An AlK X-ray source was used with a current of 20 mA and a voltage of 15 kV (300 W). The sample compartment pressure was maintained at 10−8 ÷ 10−9 Torr. High-resolution spectra for each element of interest were obtained by averaging five scans recorded with a pass energy of 20 eV and a step size of 0.1 eV. The binding energy of the C 1s peak was chosen as the reference value for all binding energies, normalized at 284.6 eV.

2.2. General Synthesis Procedures

2.2.1. General Synthesis Procedures for the of 4,4′-diazido-3,3′-dimethoxy-1,1′-biphenyl

A total of 1 equiv. of 1 (1 g) was suspended in 10 mL of HCl solution (4M) and stirred at 0–5 °C for 10 min. A total of 2.2 equiv. of sodium nitrite (0.61 g) aqueous solution was added dropwise under stirring for another 15 min at 0–5 °C. The resulting solution was added to 2.3 equiv. of sodium azide (0.59 g) in 10 mL of water and stirred at room temperature for one hour. The obtained suspension was filtered and washed with 30 mL of water to give the desired product, which was used without further purification.
Crystals 14 00144 i001
Isolated as a grey solid. Yield 98%. IR (ATR): ν (cm−1) = 2964(m), 2927(w), 2118(i), 2087(i), 1492(i), 1240(i). 1H NMR (CDCl3, 400.1 MHz, δ (ppm)): 3.95 (3H, s, OCH3), 7.04 (1H, d, 4J = 2 Hz, H-2), 7.06 (1H, d, 3J = 8 Hz, H-5), 7.11 (1H, dd, 3J = 8 Hz, 4J = 2 Hz, H-6).
13C NMR (CDCl3, 100.6 MHz, δ (ppm)): 56.1 (OCH3), 110.8 (CH-2), 119.9 (CH-6), 120.6 (CH-5), 127.8 (C-1), 138.3 (C-4), 152.1 (C-3).
HRMS (MALDI-TOF/TOF) m/z calcd for [M+Na]+ 320.100, found 320.089.
Anal. Calcd. for C14H12N6O2: C, 56.75; H, 4.08; N, 28.36. Found: C, 56.77; H, 4.07; N, 28.35.

2.2.2. General Procedure for the Synthesis of L1 and L2

Azide 2 (1 equiv, 0.2 g) was suspended in a mixture of tert-butanol/H2O (1:1, v/v, 10 mL). 1-hexyne or phenylacetylene (2.2 equiv, 0.12/0.15 g) and Cu(I) (5%) catalyst ([Cu(phen)(PPh3)2]NO3) were added. The resulting mixture was stirred at 90 °C for 24 h. A total of 25% aqueous ammonia (10 mL) was added and the formed solid was filtered, dried, and purified by crystallization from chloroform:ethanol (1:1, v/v).
1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-butyl-1H-1,2,3-triazole) L1
Crystals 14 00144 i002
Isolated as yellow crystals. Yield 92%. IR (ATR): ν (cm−1) = 3427(i), 3170(m), 2932(w), 2860(w), 1608(m), 1579(w), 1508(i), 1461(i), 1382(i), 1311(i), 1228(i), 1188(m), 1143(i), 1039(m), 1020(i), 981(m), 862(w), 815(i).
1H NMR (CDCl3, 600.1 MHz, δ (ppm)): 0.97 (3H, t, 3J = 8 Hz, CH3), 1.45 (2H, sextet, 3J = 8 Hz, CH2-14), 1.75 (2H, quintet, 3J = 8 Hz, CH2-13), 2.83 (2H, t, 3J = 8 Hz, CH2-12), 3.99 (3H, s, OCH3), 7.26 (1H, s, H-2), 7.33 (1H, dd, 3J = 8 Hz, 4J = 2 Hz, H-6), 7.89 (1H, s, H-11), 7.91 (1H, d, 3J = 8 Hz, H-5).
13C NMR (CDCl3, 150.9 MHz, δ (ppm)): 13.9 (CH3), 22.4 (CH2-14), 25.4 (CH2-12), 31.6 (CH2-13), 56.2 (OCH3), 111.2 (CH-2), 120.1 (CH-6), 122.7 (CH-11), 125.7 (CH-5), 126.4 (C-1), 141.9 (C-4), 148.0 (C-10), 151.2 (C-3).
15N NMR (CDCl3, 60.8 MHz, δ (ppm)): 244.3 (N-7), 349.9 (N-9), 360.1 (N-8)
HRMS (MALDI-TOF/TOF) m/z calcd for [M+H]+ 461.260, found 461.241.
Anal. Calcd. for C26H32N6O2: C, 67.80; H, 7.00; N, 18.25. Found: C, 67.81; H, 6.98; N, 18.24.
1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-phenyl-1H-1,2,3-triazole) L2
Crystals 14 00144 i003
Isolated as white crystals. Yield 84%. IR (ATR): ν (cm−1) = 3439(i), 3194(w), 3136(w), 2939(w), 1608(m), 1576(i), 1508(i), 1460(i), 1383(i), 1247(i), 1218(m), 1136(w), 1020(i), 982(m), 812(i), 757(i), 692(i), 576(w), 501(w).
1H NMR (CDCl3, 600.1 MHz, δ (ppm)): 4.04 (3H, s, OCH3), 7.32 (1H, d, 4J = 2 Hz, H-2), 7.36–7.39 (2H, m, H-6 and H-15), 7.48 (2H, t, 3J = 8 Hz, H-14), 7.95 (2H, d, 3J = 8 Hz, H-13), 8.00 (1H, d, 3J = 8 Hz, H-5), 8.41 (1H, s, H-11).
13C NMR (CDCl3, 100.6 MHz, δ (ppm)): 56.3 (OCH3), 111.2 (CH-2), 120.2 (CH-6), 121.7 (C-11), 125.7 (CH-5), 125.9 (CH-13), 126.2 (C-1), 128.2 (CH-15), 128.9 (CH-14), 130.6 (C-12), 142.1 (C-4), 147.5 (C-10), 151.2 (C-3).
15N NMR (CDCl3, 60.8 MHz, δ (ppm)): 246.2 (N-7), 345.8 (N-9), 364.1 (N-8)
HRMS (MALDI-TOF/TOF) m/z calcd for [M+H]+ 501.200, found 501.141.
Anal. Calcd. for C30H24N6O2: C, 71.98; H, 4.83; N, 16.79. Found: C, 71.99; H, 4.80; N, 16.80.

2.2.3. General Procedure for the Synthesis of Copper and Zinc L1 Complexes

Zn(NO3)2·6H2O or Cu(NO3)2·6H2O (4 equiv., 23.8/19.5 mg) and L1 (1 equiv., 10 mg) were dissolved in acetonitrile (1 mL) at room temperature. The clear solution was placed under static conditions for 1 day at 80 °C. After cooling, the yellow crystalline product was collected by filtration, washed with acetonitrile, and dried at room temperature.
[CuL1(NO3)2]n Yield 93%. IR (ATR): ν (cm−1) = 3450(i), 3178(m), 2954(m), 2868(w), 1602(m), 1557(i), 1498(i), 1387(i), 1290(i), 1249(i), 1082(i), 1005(i), 854(m), 812(i), 746(i).
1H NMR (DMSO-d6, 400.1 MHz, δ (ppm)): 0.93 (3H, t, 3J = 7 Hz, CH3), 1.36–1.41 (2H, m, CH2-14), 1.66 (2H, bs, CH2-13), 2.71 (2H, bs, CH2-12), 3.99 (3H, s, OCH3), 7.54 (1H, d, 3J = 7 Hz, H-6), 7.61 (1H, bs, H-2), 7.74 (1H, d, 3J = 7 Hz, H-5), 8.26 (1H, s, H-11).
13C NMR (DMSO-d6, 100.6 MHz, δ (ppm)): 13.1 (CH3), 21.2 (CH2-14), 24.1 (CH2-12), 30.5 (CH2-13), 55.9 (OCH3), 111.2 (CH-2), 119.0 (CH-6), 123.4 (CH-11), 125.2 (CH-5 and C-1), 140.7 (C-4), 147.2 (C-10), 151.2 (C-3).
HRMS (MALDI-TOF/TOF) m/z calcd for 2L1 and one Copper [M+H]+ 986.066, found 983.423 and m/z calcd for 2L1 and 2Cu [M+H]+ 1049.612, found 1043.535.
Anal. Calcd. for C26H32CuN8O8: C, 48.18; H, 4.98; N, 17.29. Found: C, 48.15; H, 4.95; N, 17.30.
[ZnL1(NO3)2]n Yield 91%. IR (ATR): ν (cm−1) = 3458(m), 3160(m), 2937(i), 2866(i), 1610(m), 1556(i), 1500(i), 1384(i), 1292(i), 1253(m), 1082(i), 1015(m), 854(m), 815(i), 740(m).
1H NMR (DMSO-d6, 400.1 MHz, δ (ppm)): 0.94 (3H, t, 3J = 8 Hz, CH3), 1.40 (2H, sextet, 3J = 8 Hz, CH2-14), 1.67 (2H, quintet, 3J = 8 Hz, CH2-13), 2.73 (2H, t, 3J = 8 Hz, CH2-12), 4.00 (3H, s, OCH3), 7.54 (1H, dd, 3J = 8 Hz, 4J = 2 Hz, H-6), 7.62 (1H, d, 4J = 2 Hz, H-2), 7.74 (1H, d, 3J = 8 Hz, H-5), 8.25 (1H, s, H-11).
13C NMR (DMSO-d6, 100.6 MHz, δ (ppm)): 13.7 (CH3), 21.8 (CH2-14), 24.6 (CH2-12), 31.1 (CH2-13), 56.4 (OCH3), 111.7 (CH-2), 119.6 (CH-6), 123.7 (CH-11), 125.7 (C-1), 125.8 (CH-5), 141.2 (C-4), 146.9 (C-10), 151.7 (C-3).
HRMS (MALDI-TOF/TOF) m/z calcd for 2L1 and 2Zn [M+H]+ 1054.280 found 1054.190.
Anal. Calcd. for C26H26ZnN8O8: C, 48.05; H, 4.96; N, 17.24. Found: C, 48.08; H, 4.93; N, 17.25.

2.2.4. General Procedure for the Synthesis of Copper L2 Complex

Cu(NO3)2·6H2O (4 equiv., 19.3 mg) and L2 (1 equiv., 10 mg) were dissolved in 1-butanol (1 mL) at room temperature. The clear solution was placed under static conditions for 2 days at 100 °C. After cooling, the yellow crystalline product was collected by filtration, washed with 1-butanol, and dried at room temperature.
[CuL2NO3]n Yield 46%. IR (ATR): ν (cm−1) = 3447(i), 3160(w), 2993(w), 2910(w), 1643(i), 1604(i), 1504(i), 1414(i), 1372(i), 1300(i), 1251(m), 1020(i), 951(m), 810(i), 768(i), 694(i), 570(m), 501(m).
1H NMR (DMSO-d6, 400.1 MHz, δ (ppm)): 4.05 (3H, s, OCH3), 7.40 (1H, t, 3J = 7 Hz, H-15), 7.51 (2H, t, 3J = 7 Hz, H-14), 7.62 (1H, d, 3J = 8 Hz, H-6), 7.70 (1H, bs, H-2), 7.85 (1H, d, 3J = 8 Hz, H-5), 7.98 (2H, d, 3J = 7 Hz, H-13), 9.00 (1H, s, H-11).

2.3. Safety Notes

Some organic azides are thermally and photochemically labile and can quickly break down with heat to release significant amounts of nitrogen. Additionally, some azides, especially low-molecular-weight azides, exhibit impact sensitivity and are frequently explosive. CAUTION! Even though we handled them without any issues, organic azides and compounds high in azide are known to be extremely explosive. Strong acids, certain transition metal species, or concentration in a vacuum can all catalyze the decomposition of organic azides. Procedures should be performed in a well-ventilated hood behind a safety shield, together with the proper personal protective equipment. Before starting any experiments, all employees should receive rigorous training in the usage of azides [27].

3. Results and Discussions

Synthesis of 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-butyl-1H-1,2,3-triazole), referred to as ligand 1 (L1), and 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-phenyl-1H-1,2,3-triazole), referred to as ligand 2 (L2), was achieved via a two-step synthetic pathway, as shown in Scheme 1.
The proposed synthetic pathway involved the diazotization of the amino groups of the starting 3′-dimethoxy-[1,1′-biphenyl]-4,4′-diamine 1 using sodium nitrite, followed by addition of sodium azide, leading to the desired bisazide 2 in a 98% yield. The second step consisted in the click reaction of 4,4′-diazido-3,3′-dimethoxy-1,1′-biphenyl 2 with 1-hexine (L1) and phenylacetylene (L2), using a Cu(I) catalyst, affording the desired compounds in 92% and 84% yields, respectively.
The success of the click reaction between bisazide 2 and 1-hexine (L1) and phenylacetylene (L2), with the formation of the 1,2,3-triazole cycle, was verified through NMR spectroscopy. In the proton spectrum corresponding to compound L1 (Figure S3), the CH proton from the newly formed triazole cycle resonated in the low-field region, at 7.90 ppm. Aromatic protons have resonance signals in the interval 7.0–8.0 ppm, their number and multiplicities being in accordance with the substitution pattern. Thus, as can be seen in Figure S3, the three aromatic signals were assigned as follows: singlet at 7.26 ppm to H-2, doublet of doublets centered at 7.33 ppm to H-6, and doublet centered at 7.91 ppm to H-5. In the aliphatic spectral region, five signals are visible being assigned as follows: methoxy protons to the singlet from 3.99 ppm, butyl terminal CH2 group to the triplet from 2.82 ppm, butyl middle CH2 groups to the quintet and sextet from 1.75 and 1.45 ppm, butyl CH3 group to the triplet from 0.97 ppm.
Similar with the proton spectrum, the number of signals and chemical shifts values obtained in the 1D carbon NMR spectrum support the proposed structures for L1 and L2. The 13C NMR spectrum recorded for compound L1 is presented in Figure S4, the signal assignments being annotated on the figure. Five resonance signals are visible in the aliphatic region, between 10 and 60 ppm, assigned to butyl and methoxy carbon atoms. Four protonated and four quaternary carbon atoms have resonance signals in the low-field region, in the interval 110–150 ppm. The two carbon atoms from the newly formed 1,2,3-triazole cycle are assigned at 122 ppm (CH) and 148 ppm (C), based on the three-bond proton–carbon correlations with butyl residue.
Through space, proton–proton NOE and long-range proton–nitrogen correlations offered additional information supporting the formation of the 1,2,3-triazole cycle and its covalent link to the phenyl ring. In the 2D NOESY spectrum (Figure S5) recorded for L1, through space, NOE correlation signals are visible between 1,2,3-triazole CH proton and methoxy protons from the phenyl ring. As NOE interactions occur through dipolar couplings, the distance between these protons has to be less than 5 Å, meaning they are close to each other. Two methylene groups (CH2-12 and CH2-13) from butyl residue also show NOE correlation signals with triazole CH proton, supporting butyl spatial proximity to the nitrogen-containing heterocycle.
Proton–nitrogen three-bond correlation experiments provided definite proof for the covalent link between 1,2,3-triazole cycle and the phenyl ring. Three-bond correlation signals between N-7 (244 ppm) from triazole cycle and H-5 proton from the phenyl ring were visible in both L1 and L2 spectra (Figures S6 and S9). The remaining two nitrogen atoms resonate at 350 and 360 ppm, as obtained from three-bond correlations with butyl CH2 protons and triazole CH proton, respectively. These nitrogen chemical shifts values are similar to previously reported 15N and 14N chemical shifts for other 1,2,3-triazole compounds [28].
For both compounds L1 and L2, only one set of signals was observed in proton and carbon NMR spectra, confirming the symmetry of click reaction products. The exact NMR signal assignments, as obtained from proton–proton and proton–carbon 2D correlation experiments like H,H-COSY, H,C-HSQC, and long-range H,C-HMBC, are included in the Experimental Section.
MALDI-MS analysis was used to obtain additional information supporting the proposed structures. Since the molecular ion occurs in the positive mode, only positive ions were examined. A good correlation between the estimated mass and the experimental ones was found for each compound (experimental section and Supplementary Materials SI, Figures S21–S25).
The potential of the two novel 1,2,3-triazole derivatives to act as linkers for coordination polymers was evaluated using Cu(II) and Zn(II) nitrate. It was found that the use of a ligand:metal ratio of 1:4, acetonitrile (for L1) and 1-butanol (in case of L2) as solvents, and a temperature of 80–100 °C led to the formation of crystalline compounds [CuL1(NO3)2]n and [ZnL1(NO3)2]n, as well as [CuL2NO3]n. In all three cases, the crystals were suitable for single-crystal X-ray diffraction analysis. In the case of L2 and Zn, we were not able to obtain a complex.
The first piece of evidence that supported the formation of a complex was provided by the FT-IR spectra of the isolated compound. Thus, the bands corresponding to C–H stretching of triazole rings were shifted to higher wavenumbers, while the other bands were shifted to lower wavenumbers due to the new metal–heteroatom bond, which stiffens the newly formed structure. In addition, a new band was observed at 856–742 cm−1, assigned to the newly formed ligand–metal bond [9].
The synthesized zinc and copper complexes were also analyzed through NMR spectroscopy. As zinc is a well-known diamagnetic ion, no relevant changes were observed in the proton or carbon NMR spectra recorded for the [ZnL1(NO3)2]n (Figures S12 and S13). However, a significant line broadening was observed for the [CuL1(NO3)2]n, copper being a paramagnetic ion. In the proton spectrum recorded for the [CuL1(NO3)2]n, the two singlets (CH from triazole cycle and methoxy) had linewidth values of 5 Hz (CH from triazole) and 3 Hz (methoxy), as compared with the free L1, where the linewidths for both singlets were 2 Hz. Moreover, the signal shapes were affected and only splitting due to three-bond vicinal couplings, which were observed for the phenyl protons. The signals for the butyl residue were broadened in a similar manner, complex-splitting patterns such as quintet and sextet being no longer visible (Figure S12). In the carbon NMR spectrum corresponding to [CuL1(NO3)2]n, the most affected signals were those from the 1,2,3-triazole cycle. Both signals suffered severe broadening accompanied by loss of intensity, so much that the quaternary carbon’s signal from 147 ppm was almost lost in the baseline (Figure S13). All the carbon atom signals suffered a slight upfield shift, induced by the copper ion presence, compared with the free L1. A similar broadening was observed for the [CuL2NO3]n (Figure S14).
The chemical composition and the solid-state structures for both ligands, as well as for the three synthesized metal complexes, were obtained by single-crystal X-ray analysis. The results of X-ray diffraction analysis for L1 and L2 are shown in Figure 1.
In the crystal, the neutral L1 molecules are interacting through CH---N intermolecular H-bonds to form discrete centro-symmetric associates, as shown in Figure 2a. In the case of L2, the crystal structure has revealed the presence of two-dimensional supramolecular layers parallel to 101 planes. Each layer is formed due to π-π stacking interactions involving both phenyl and triazole aromatic rings of adjacent molecules. A view of the 2D supramolecular layer in the crystal structure of L2 is shown in Figure 2b.
According to X-ray crystallography, [CuL1(NO3)2]n and [ZnL1(NO3)2]n complexes are isostructural. They crystallize in C2/c space group with close unit cell parameters. Therefore, below, as an example, the structure of [CuL1(NO3)2]n will be characterized. A view of the asymmetric part in the crystal structure is shown in Figure 3. It comprises one metal cation, two independent halves of the L1 ligand, and two NO3− anions. There are no co-crystalized solvent molecules present in the crystal. The coordination polyhedron of the Cu(II) atom involves two nitrogen atoms from triazole rings at Cu1-N1 of 2.018(3) Å, and two O,O’-semibidentate nitrate anions coordinated with a shorter Cu1-O4 1.959(3) Å distance and a longer Cu1-O2 2.479(9) Å distance. Given that each nitrate anion occupies only one coordination position, one can consider that the Cu(II) atom exhibits a distorted tetrahedral geometry.
Further analysis of the crystal structure has revealed the presence of a zigzag coordination polymer, formed due to self-assembling of asymmetric units over the inversion center, which coincides with the position of the metal atom. A view of the 1D coordination polymer is depicted in Figure 4. In the crystal, they are interacting through weak C-H···O hydrogen bonding, where the nitrate oxygen atoms act as acceptors of protons, leading to the formation of a complex and quite dense 3D supramolecular architecture. As expected, the use of the “Solvent mask” routine available in Olex2 (for probe radius of 1.2 Å and resolution of 0.2 Å) indicates the lack of the solvent-accessible voids in both [CuL1(NO3)2]n and [ZnL1(NO3)2]n crystals.
The results of X-ray diffraction analysis for [CuL2NO3]n are shown in Figure 5. The asymmetric part consists of one copper atom, two independent halves of the L2 ligand, and one NO3− anion. The composition, as well as the charge balance, is unequivocally consistent with the 1/1 Cu/NO3− ratio, indicating the Cu+ oxidation state. Cooper adopts a typical for Cu(I) distorted trigonal planar coordination provided by two nitrogen atoms of triazole rings and oxygen atom from nitrate anion with Cu1-N1 1.906(4) Å, Cu1-N4 1.931(3) Å, and Cu1-O3 2.140(5) Å bond distances. The copper atom is displaced by 0.081(2) Å from the N1N4O3 plane, indicating a strong coplanarity with donor atoms. Further analysis of the structure indicates that this compound also represents a linear coordination polymer [CuL2NO3]n, formed through self-assembling of the asymmetric units over the inversion centers located at the middle points of C4-C4′ (1 − x, 2 − y, − z) and C19-C19′ (1 − x, 1 − y, 3 − z) bonds, as shown in Figure 6.
The crystal motif is characterized by the parallel packing of two-dimensional supramolecular layers consolidated via π-π interactions involving phenyl and triazole rings of the adjacent coordination chains, which is evidenced by centroid-to-centroid distances of 3.7857(5) Å and 3.8005(4) Å. A partial view of the 2D supramolecular architecture is shown in Figure 7. Regardless of the nature of the metal center and the composition of the ligand, the crystal packing of [CuL2NO3]n resembles well that observed for the compounds [CuL1(NO3)2]n and [ZnL1(NO3)2]n. The main crystal structure motif is also characterized as a 3D supramolecular network that essentially results from a dense parallel packing of 2D layers driven by weak C-H···O hydrogen bonds, involving nitrate oxygen atoms as acceptors. Similarly, as detected by Olex2, there are no free voids accessible for the solvent molecules in the crystal of [CuL2NO3]n.
The powder X-ray diffraction (PXRD) analysis of synthesized compounds provides important information about purity. The PXRD patterns of the synthesized compounds are shown in Figure 8 and Figure S15. The diffraction peaks of the synthesized Zn complex are in good agreement with the simulated data (Figure 8). In the case of [CuL1(NO3)2]n (Figure S15), apart from a visible peak broadening due to the small crystallite size, some discrepancies could be observed between the simulated and measured data, most notable being the presence of a large peak at approximatively 7.6° 2θ. This observation indicates the presence of an additional phase in the measured sample. According to the EPR spectrum (Figure 9, broad signal in low-field region), this additional phase could indicate the presence of binuclear complexes corresponding to dimers.
The thermal stability and the pathways of thermal decomposition of all synthetized compounds were investigated by means of the TGA curves and their corresponding first derivative (DTG) curves. The first mass loss stages of around 2–3% correspond to thermal history removal of the samples. Bisazide 2 showed the lowest onset thermal degradation temperature (Tonset~133 °C) and degradation stage number (III), with a total value of structural mass loss (Wm) around 58% and residue value of 39.04% (Figure S16, Table S2). The TGA profiles of isostructural compounds L1 and L2 (Figures S17 and S18) show similar and highest Tonset values (~318 °C and ~307 °C), the difference being in mass loss, residue value (Wrez) (48.28% for L2 vs. 22% for L1), and additional thermal degradation stages (IVth for L1 and Vth for L2) (Table S2). Also, the TGA profiles of isostructural complexes [CuL1(NO3)2]n and [ZnL1(NO3)2]n are similar, with some differences in the mass loss, induced by the different metals (Figures S19 and S20, Table S2). The decomposition process of the framework and organic ligand takes place around 200 °C, in the case of [CuL1(NO3)2]n, and around 250 °C, in the case of [ZnL1(NO3)2]n, respectively. Along with increasing the thermal decomposition temperature, the presence of Zn induced a supplementary degradation stage (Stage VI) of the organic ligand in [ZnL1(NO3)2]n and a slightly lower residue value compared to that of the [CuL1(NO3)2]n complex (41.02% vs. 49.88%), but comparable to those of bisazide 2 (39.04%) and ligand L2 (48.28%), respectively. Nonetheless, as expected, the presence of the metals induced a general increase in the residue (Wrez) values, considerably higher than that of ligand L1 (22%) (Table S2). The TGA curves of the synthesized complexes showed mass losses of ~18%, 8%, and 15% in the interval 201–397 °C for copper complex [CuL1(NO3)2]n, and losses of ~15%, 9%, and 19% in the interval 248–366 °C for zinc complex [ZnL1(NO3)2]n, respectively, which can be attributed to the loss of nitrate moieties in the molecules, followed by the complete degradation of the organic framework upon further heating up to 700 °C (Table S2).
The EPR spectrum of [CuL1(NO3)2]n was recorded in DMSO at room temperature. Figure 9 highlights the characteristic spectrum of copper complex based on azole ligands [29], in which it is difficult to distinguish the g parameter characteristic of the axial structure because of the liquid solution that masks the anisotropy effect of the molecular structure. A broad EPR signal is centered on the average value of g = 2.17719, in which poorly resolved secondary signals, characteristic of allowed transitions (Δms = ±1) related to the complex, are observed [30]. At 1605 G, one can observe an additional broad signal of low intensity, centered on g = 4.35 (Figure 9, detailed low-field region). Previous studies on Cu2+-based complexes showed that this weak signal from g values of 4–4.5 (1600–1650 G) can be attributed to forbidden transitions (Δms = ±2) related to the electronic coupling of two copper ions close to a distance <7 Å [31,32]. Such results suggest the existence of aggregation phenomena or the formation of binuclear complexes corresponding to dimers [33].
Atoms inside a surface layer up to 10 nm have a core electron-binding energy that is determined by XPS measurements. The relationship between the binding energy (BE) and the atomic potential reveals details about the environment and atomic oxidation state. Small variations in spatial and electrical structure of the compounds can be detected due to XPS sensitivity.
The full scan of [CuL1(NO3)2]n (Figure S26) and [ZnL1(NO3)2]n (Figure S27) revealed the presence of Cu(II) or Zn(II) and C, N, and O.
The core level spectrum in the Cu 2p region shows the two main binding energies of 934.2 with a satellite peak at 942.4, and 954 with a satellite peak at 962.6 eV corresponding to Cu 2p3/2 and Cu 2p1/2 from the complex. The C 1s core signifies four types of carbon atoms, sp3 (C-H, C-O, C-C), sp2 (C=C, C=N), Car-Car, and sp (C≡N), with binding energies at 283.3 eV. The N1s core shows two energy states as it is bounded in two modes, one covalent in the organic frame and one coordinated to Cu(II) ions, with binding energies of 399.3 and 405.2 eV. The O1s core level spectrum shows one band of BE = 531.6 eV corresponding to the etheric oxygen atom [34].
The core level spectrum in the Zn 2p region shows the two main binding energies of 1022.5 and 1045.9 eV corresponding to Zn 2p3/2 and Zn 2p1/2, respectively. The C1s (283.3 eV), N1s (399.4 and 405.6 eV), and O1s (531.6eV) core are similar with the ones in the copper complex, as the structures are isostructural (see Supplementary Materials) [35,36].

4. Conclusions

In this study, we synthesized and characterized two bis(triazole) ligands, 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl) bis(4-butyl-1H-1,2,3-triazole) (L1) and 1,1′-(3,3′-dimethoxy-[1,1′-biphenyl]-4,4′-diyl)bis(4-phenyl-1H-1,2,3-triazole) (L2), as well as their coordination polymers, with Cu(II) and Zn(II). The ligands and metal complexes were characterized by X-ray diffraction, NMR-, FTIR-spectroscopy, MS-spectrometry, and TG-DTG analyses, and in the case of [CuL1(NO3)2]n and [ZnL1(NO3)2]n, through XPS, in order to confirm the proposed structures. X-ray diffraction analysis of the [CuL1(NO3)2]n and [ZnL1(NO3)2]n crystal structures revealed the presence of zigzag coordination polymers, formed due to self-assembling of asymmetric units over the inversion centers, which coincides with the position of the metal atoms.
For L2, we obtained an unexpected linear coordination polymer with Cu(I) starting from Cu(II). The crystal structure of this complex indicated one copper atom, two independent halves of the L2 ligand, and one NO3− anion. The composition as well as the charge balance were consistent with the 1/1 Cu/NO3− ratio, indicating a Cu+ oxidation state.
Within the crystals, additional interactions between these polymers only occur through weak hydrogen bonding, creating a 3D supramolecular network without any accessible solvent areas. Our ongoing research aims to investigate the interactions of these organic ligands with different metal salts, targeting the synthesis of 2D or 3D coordination polymers. This approach has the potential to produce materials with different porosities.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/2073-4352/14/2/144/s1, Figure S1: FT-IR spectra of ligand L1 and complexes [CuL1(NO3)2]n and [ZnL1(NO3)2]n; Figure S2: FT-IR spectra of ligand L2 and complex [CuL2NO3]n; Figure S3: 1H-NMR spectrum corresponding to compound L1, recorded in CDCl3, at 600.1 MHz. Signals assignments are annotated on the figure; Figure S4: 13C-NMR spectrum corresponding to compound L1, recorded in CDCl3, at 150.9 MHz. Signals assignments are annotated on the figure; Figure S5: H,H-NOESY spectrum recorded for compound L1, with the insert showing the NOE correlation signals between 1,2,3-triazole proton and methoxy and butyl protons; Figure S6: Detailed spectral region of 1H,15N-HMBC spectrum corresponding to compound L1, showing the proton-nitrogen two and three bonds couplings used to determine the chemical shifts values for nitrogen atoms; Figure S7: 1H-NMR spectrum corresponding to compound L2, recorded in CDCl3, at 600.1 MHz. Signals assignments are annotated on the figure; Figure S8: 13C-NMR spectrum corresponding to compound L2, recorded in CDCl3, at 100.6 MHz; Figure S9: Detailed spectral region of 1H,15N-HMBC spectrum corresponding to compound L2, showing the proton-nitrogen two and three bounds couplings used to determine the chemical shifts values for nitrogen atoms; Figure S10: 1H-NMR spectrum corresponding to bisazide 2, recorded in CDCl3, at 600.1 MHz. Signals assignments are annotated on the figure; Figure S11: 13C-NMR spectrum corresponding to bisazide 2, recorded in CDCl3, at 100.6 MHz; Figure S12: Overlapped 1H-NMR spectra recorded at 400.1 MHz, in DMSO-d6, for free L1 (a), [ZnL1(NO3)2]n complex (b) and [CuL1(NO3)2]n complex (c). For copper complex, significant line broadening causing the modification of splitting patterns is observed for all the signals; Figure S13: Overlapped 13C-NMR spectra recorded at 100.6 MHz, in DMSO-d6, for free L1 (a), [ZnL1(NO3)2]n complex (b) and [CuL1(NO3)2]n complex (c). For copper complex, significant line broadening is observed for 1,2,3-triazole cycle carbons; Figure S14: Overlapped 1H-NMR spectra recorded at 400.1 MHz, in DMSO-d6, for free L2 (a) and [CuL2NO3]n complex (b). For cupper complex, significant line broadening causing the modification of splitting patterns is observed for two signals; Figure S15: Powder XRD for [CuL1(NO3)2]n complex; Figure S16: TG-DTG curves of bisazide 2; Figure S17: TG-DTG curves of ligand L1; Figure S18: TG-DTG curves of ligand L2; Figure S19: TG-DTG curves of [CuL1(NO3)2]n; Figure S20: TG-DTG curves of [ZnL1(NO3)2]n; Figure S21: Maldi-MS spectrum of bisazide 2; Figure S22: Maldi-MS spectrum of L1; Figure S23: Maldi-MS spectrum of L2; Figure S24: Maldi-MS spectrum of [CuL1(NO3)2]n; Figure S25: Maldi-MS spectrum of [ZnL1(NO3)2]n; Figure S26. XPS spectra of [CuL1(NO3)2]n, full scan, C1s, N1s, O1s and Cu2p (in this order); Figure S27. XPS spectra of [ZnL1(NO3)2]n, full scan, C1s, N1s, O1s and Zn2p (in this order); Table S1: Bond distances (Å) and angles (°) for [CuL2NO3]n complex, [ZnL1(NO3)2]n complex, L1 ligand, [CuL1(NO3)2]n complex, L2 ligand, Table S2. Data extracted from TG-DTG experiments.

Author Contributions

Conceptualization, M.C.A.-M.; methodology, M.C.A.-M. and A.N.; validation, R.D. and A.N.; investigation, A.N., I.-A.D., S.S., C.-D.V., A.F. and I.-C.M.; data curation, M.C.A.-M.; writing—original draft preparation, M.C.A.-M., A.N. and S.S.; writing—review and editing, M.C.A.-M., A.N. and S.S.; All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The raw data supporting the conclusions of this article will be made available by the authors on request. CCDC-2265351-2265355 contain the supplementary crystallographic data for this contribution. These data can be obtained free of charge via www.ccdc.cam.ac.uk, accessed on 19 December 2023 (or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +(44)-1223-336-033; or [email protected]).

Acknowledgments

Access to the research infrastructure developed through the European Social Fund for Regional Development, Competitiveness Operational Programme Axis 1, Action: 1.1.3, Project “Infra SupraChem Lab—Center for Advanced Research in Supramolecular Chemistry” (Contract 339/390015/25.02.2021, cod MySMIS: 108983) is gratefully acknowledged.

Conflicts of Interest

The authors declare no conflicts of interest.

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Crystals 14 00144 sch001
Scheme 1. The synthetic pathway for the preparation of ligands L1 and L2.
Scheme 1. The synthetic pathway for the preparation of ligands L1 and L2.
Crystals 14 00144 sch001
Crystals 14 00144 g001
Figure 1. X-ray molecular structure of L1 (a) and L2 (b) with atom labeling scheme and thermal ellipsoids at 50% level. Only one component of disordered fragment in L1 is shown.
Figure 1. X-ray molecular structure of L1 (a) and L2 (b) with atom labeling scheme and thermal ellipsoids at 50% level. Only one component of disordered fragment in L1 is shown.
Crystals 14 00144 g001
Crystals 14 00144 g002
Figure 2. Supramolecular architectures in the crystal structures of L1 and L2. (a) H-bonding between two centro-symmetrically related L1 molecules. H-bond parameters: C21-H···N5 [C21-H 0.93 Å, H···N5 2.43 Å, C21···N5(2 − x, 1 − y, −z) 3.26(1) Å, ∠C21HN5 148.0 o]. (b) Partial view of two-dimensional supramolecular layer in the crystal structure of L2. Centroid-to-centroid distances (dotted orange lines) vary in the range between 3.930 and 4.032 Å. Hydrogen atoms were omitted for clarity.
Figure 2. Supramolecular architectures in the crystal structures of L1 and L2. (a) H-bonding between two centro-symmetrically related L1 molecules. H-bond parameters: C21-H···N5 [C21-H 0.93 Å, H···N5 2.43 Å, C21···N5(2 − x, 1 − y, −z) 3.26(1) Å, ∠C21HN5 148.0 o]. (b) Partial view of two-dimensional supramolecular layer in the crystal structure of L2. Centroid-to-centroid distances (dotted orange lines) vary in the range between 3.930 and 4.032 Å. Hydrogen atoms were omitted for clarity.
Crystals 14 00144 g002
Crystals 14 00144 g003
Figure 3. The asymmetric unit in the crystal structure of [CuL1(NO3)2]n showing the metal coordination with atom labeling scheme and thermal ellipsoids at 50% level. Symmetry-generated atoms are shown with faded colors. Symmetry codes: (i) 1 − x, y, 0.5 − z.
Figure 3. The asymmetric unit in the crystal structure of [CuL1(NO3)2]n showing the metal coordination with atom labeling scheme and thermal ellipsoids at 50% level. Symmetry-generated atoms are shown with faded colors. Symmetry codes: (i) 1 − x, y, 0.5 − z.
Crystals 14 00144 g003
Crystals 14 00144 g004
Figure 4. The partial view of [CuL1(NO3)2]n 1D coordination polymer. Hydrogen atoms were omitted for clarity.
Figure 4. The partial view of [CuL1(NO3)2]n 1D coordination polymer. Hydrogen atoms were omitted for clarity.
Crystals 14 00144 g004
Crystals 14 00144 g005
Figure 5. Asymmetric part in the crystal structure of [CuL2NO3]n with atom labeling scheme and thermal ellipsoids at 50% level.
Figure 5. Asymmetric part in the crystal structure of [CuL2NO3]n with atom labeling scheme and thermal ellipsoids at 50% level.
Crystals 14 00144 g005
Crystals 14 00144 g006
Figure 6. The structure of 1D coordination polymer [CuL2NO3]n. Hydrogen atoms are omitted for clarity.
Figure 6. The structure of 1D coordination polymer [CuL2NO3]n. Hydrogen atoms are omitted for clarity.
Crystals 14 00144 g006
Crystals 14 00144 g007
Figure 7. The structure of 2D supramolecular layer in the crystal structure of [CuL2NO3]n. Hydrogen atoms are omitted for clarity.
Figure 7. The structure of 2D supramolecular layer in the crystal structure of [CuL2NO3]n. Hydrogen atoms are omitted for clarity.
Crystals 14 00144 g007
Crystals 14 00144 g008
Figure 8. Powder XRD of [ZnL1(NO3)2]n in simulated and experimental comparison.
Figure 8. Powder XRD of [ZnL1(NO3)2]n in simulated and experimental comparison.
Crystals 14 00144 g008
Crystals 14 00144 g009
Figure 9. EPR spectrum of [CuL1(NO3)2]n complex in DMSO at room temperature and detailed spectrum with the small-intensity signal from the low-field region.
Figure 9. EPR spectrum of [CuL1(NO3)2]n complex in DMSO at room temperature and detailed spectrum with the small-intensity signal from the low-field region.
Crystals 14 00144 g009
Table 1. Crystal data and details of data collection.
Table 1. Crystal data and details of data collection.
ParameterL1L2[CuL1(NO3)2]n[ZnL1(NO3)2]n[CuL2NO3]n
empirical formulaC26H32N6O2C30H24N6O2C26H32CuN8O8C26H32ZnN8O8C30H24CuN7O5
Fw460.57500.55648.13649.96626.10
space groupP21/nP21/cC2/cC2/cP-1
a [Å]9.993(3)13.8920(13)11.1504(11)11.1122(10)11.8358(13)
b [Å]9.330(2)12.1417(7)15.5765(10)15.6283(9)12.2359(10)
c [Å]27.230(9)15.6437(10)17.6588(14)17.1081(11)12.2813(12)
α [°]9090909061.105(9)
β [°]94.02(2)112.007(9)108.143(10)106.051(8)74.812(9)
γ [°]9090909061.476(10)
V [Å3]2532.7(12)2446.4(3)2914.6(4)2855.2(4)1367.3(3)
Z44442
rcalcd [g cm−3]1.2081.3591.4771.5121.521
Crystal size [mm]0.40 × 0.30 × 0.050.40 × 0.25 × 0.050.35 × 0.30 × 0.200.40 × 0.30 × 0.300.40 × 0.15 × 0.08
T [K]297297180200297
μ [mm−1]0.0790.0890.8120.9240.854
2Θ range [°]4.252 to 46.5144.376 to 59.1324.65 to 50.054.62 to 50.0543.792 to 50.052
Reflections collected831915,5716313594913,680
Independent reflections3625 [Rint = 0.0505]5227 [Rint = 0.0534]2582 [Rint = 0.0367]2524 [Rint = 0.0215]4831 [Rint = 0.0760]
Data/restraints/parameters3625/10/3195727/0/3452582/41/2132524/3/2154831/0/390
R1 [a]0.09480.06800.05450.03420.0674
wR2  [b]0.24420.14580.13060.08220.1870
GOF [c]1.0601.0321.0971.0461.022
Largest diff. peak/hole/e Å−30.28/−0.230.16/−0.180.73/−0.370.65/−0.280.55/−0.30
CCDC no.22653512265352226535322653542265355
a R1 = Σ||Fo| − |Fc||/Σ|Fo|. b wR2 = {Σ[w(Fo2 − Fc2)2]/Σ[w(Fo2)2]} 1/2. c GOF = {Σ[w(Fo2 − Fc2)2]/(n − p)}1/2, where n is the number of reflections and p is the total number of parameters refined.
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Al-Matarneh, M.C.; Nicolescu, A.; Dascalu, I.-A.; Shova, S.; Varganici, C.-D.; Fifere, A.; Danac, R.; Marinas, I.-C. Synthesis of New Zinc and Copper Coordination Polymers Derived from Bis (Triazole) Ligands. Crystals 2024, 14, 144. https://doi.org/10.3390/cryst14020144

AMA Style

Al-Matarneh MC, Nicolescu A, Dascalu I-A, Shova S, Varganici C-D, Fifere A, Danac R, Marinas I-C. Synthesis of New Zinc and Copper Coordination Polymers Derived from Bis (Triazole) Ligands. Crystals. 2024; 14(2):144. https://doi.org/10.3390/cryst14020144

Chicago/Turabian Style

Al-Matarneh, Maria Cristina, Alina Nicolescu, Ioan-Andrei Dascalu, Sergiu Shova, Cristian-Dragos Varganici, Adrian Fifere, Ramona Danac, and Ioana-Cristina Marinas. 2024. "Synthesis of New Zinc and Copper Coordination Polymers Derived from Bis (Triazole) Ligands" Crystals 14, no. 2: 144. https://doi.org/10.3390/cryst14020144

APA Style

Al-Matarneh, M. C., Nicolescu, A., Dascalu, I. -A., Shova, S., Varganici, C. -D., Fifere, A., Danac, R., & Marinas, I. -C. (2024). Synthesis of New Zinc and Copper Coordination Polymers Derived from Bis (Triazole) Ligands. Crystals, 14(2), 144. https://doi.org/10.3390/cryst14020144

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