**3. Materials and Methods**

**General.** All reagents but acetonitrile were obtained from commercial sources (Aldrich and Fluorochem) and used as received. Acetonitrile was dried over molecular sieves [23]. In the case of the 2-amino-1-butanol reagent, a racemic mixture was used. The copper starting material, [Cu(quin)2(H2O)], was synthesized as previously reported [24]. Infrared (IR) spectra were recorded with the ATR module in the 4000–400 cm−<sup>1</sup> spectral range on a Bruker Alpha II FT-IR spectrophotometer (Bruker, Manhattan, MA, USA). No corrections were made to the spectra. The spectra of all reveal strong bands in the 1560–1520 and 1370–1360 cm−<sup>1</sup> spectral regions, which may be assigned as the νas(COO−) and νs(COO−) absorptions of the ionized quinaldinate. The engagement of the OH and NH3 <sup>+</sup> functional groups in hydrogen bonding prevents unambiguous identification of the stretching/deformation bands of these functional groups. 1H nuclear magnetic resonance (NMR) spectra were recorded at 500 MHz on a Bruker Avance III 500 (Bruker BioSpin GmbH, Rheinstetten, Germany). The solvent was (CD3)2SO (DMSO-*d*6) containing 0.03% tetramethylsilane (TMS), and all spectra were referenced to the central peak of the residual resonance for DMSO-*d6* at 2.50 ppm [25]. 1H NMR spectra were processed using the MestReNova program [26]. Chemical shifts (δ) are given in ppm and coupling constants (*J*) in Hz. Multiplicities are labeled as follows: s = singlet, d = doublet, t = triplet, dd = doublet of doublet, and m = multiplet. Elemental analysis CHN was performed on a Perkin-Elmer 2400 II analyzer. Powder X-ray diffraction (PXRD) patterns were collected on a PANanlytical X'Pert PRO MD diffractometer (PANALYTICAL, Almelo, The Netherlands) using monochromatised Cu-K*α* radiation (*λ* = 1.5406 Å). Thermogravimetric analyses were performed on a Mettler Toledo TG/DSC 1 instrument (Mettler Toledo, Schwerzenbach, Switzerland). Samples were placed into a 150 μL platinum crucible. Initial masses of samples were around 10 mg. Samples were heated from 25 to 450 ◦C with a heating rate of 10 ◦C min−<sup>1</sup> and the furnace was purged with air at a flow rate of 50 mL min<sup>−</sup>1. The baseline was subtracted. All three salts are stable up to about 120 ◦C and then the decomposition processes take place. No phase transitions were observed in the 25–120 ◦C temperature range.

**(3a1pOHH)quin (1)**. Quinaldinic acid (100 mg, 0.58 mmol), methanol (10 mL), and 3-amino-1-propanol (88 μL) were added to an Erlenmeyer flask. The mixture was stirred until all the solid was consumed. The resulting solution was left to stand at ambient conditions. On the following day, it was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. Colorless crystals of (3a1pOHH)quin were filtered off. Yield: 106 mg, 74%. Notes. The identity of the product was confirmed by PXRD (Figure S1). Single crystals of **1** were obtained as follows. A Teflon container was filled with CuO (50 mg, 0.63 mmol), quinaldinic acid (120 mg, 0.69 mmol), acetonitrile (7.5 mL), and 3 amino-1-propanol (150 mg). The container was closed and inserted into a steel autoclave, which was heated for 24 h at 105 ◦C. Afterwards, the reaction mixture was allowed to cool slowly to room temperature. Black solid was filtered off, and the resulting green filtrate was concentrated under reduced pressure on a rotary evaporator. The concentrate was stored at 4 ◦C. A mixture of colorless crystals of (3a1pOHH)quin (**1**) and blue needle-like crystals of *trans*-[Cu(quin)2(3a1pOH)2] was obtained. 1H NMR (500 MHz, DMSO-*d*<sup>6</sup> with 0.03% *v/v* TMS): δ 8.30 (1H, d, *J* = 8.4 Hz, quin−), 8.12 (1H, d, *J* = 8.4 Hz, quin−), 8.04 (1H, d, *J* = 8.4 Hz, quin−), 7.95 (1H, dd, *J* = 8.2, 1.1 Hz, quin−), 7.74–7.71 (1H, m, quin−), 7.60–7.57 (1H, m, quin−), 3.50 (2H, t, *J* = 6.0 Hz, 3a1pOHH+), 2.95 (2H, t, *J* = 7.3 Hz, 3a1pOHH+), 1.80–1.74 (2H, m, 3a1pOHH+) ppm. Elemental analysis calcd. for C13H16N2O3 (%): C, 62.89; H, 6.50; N, 11.28. Found (%): C, 62.80; H, 6.38; N, 11.35. IR (ATR, cm−1): 3352m, 3061m, 2989m, 2947m, 2888m, 2745m, 2503w, 2090w, 1593s, 1559s, 1519s, 1502s, 1475m, 1462s, 1425s, 1384s, 1372vs, 1335s, 1298m, 1276m, 1214m, 1184m, 1168s, 1145w, 1129w, 1104m, 1068s, 1042m, 1023m, 1001m, 950w, 903s, 891s, 878m, 849m, 790vs, 776vvs, 746s, 629s, 592s, 541w, 530m, 520s, 500w, 477m.

**(2a1bOHH)quin (2)**. Quinaldinic acid (100 mg, 0.58 mmol), methanol (10 mL), and 2 amino-1-butanol (109 μL) were added to an Erlenmeyer flask. The mixture was stirred until

all the solid was consumed. The resulting solution was left to stand at ambient conditions. On the following day, it was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. Colorless, needle-like crystals of (2a1bOHH)quin were filtered off. Yield: 116 mg, 77%. Notes. PXRD confirmed that the product is mostly **2b** polymorph (Figure S2). Single crystals of **2a** and **2b** polymorphs were obtained as follows. [Cu(quin)2(H2O)] (50 mg, 0.12 mmol), nitromethane (7.5 mL) and 2-amino-1-butanol (0.25 mL) were added to an Erlenmeyer flask. The mixture was stirred thoroughly until all the solid was consumed. After a few days, a mixture of crystals of **2a** and **2b** polymorphs was obtained. 1H NMR (500 MHz, DMSO-*d*<sup>6</sup> with 0.03% *v/v* TMS): δ 8.30 (1H, d, *J* = 8.4 Hz, quin−), 8.08 (1H, d, *J* = 8.5 Hz, quin−), 8.00 (1H, d, *J* = 8.4 Hz, quin−), 7.95 (1H, dd, *J* = 8.1, 1.4 Hz, quin−), 7.76– 7.72 (1H, m, quin−), 7.60–7.57 (1H, m, quin−), 3.64 (1H, dd, *J* = 11.7, 3.8 Hz, 2a1bOHH+), 3.50 (1H, dd, *J* = 11.7, 6.2 Hz, 2a1bOHH+), 3.04–2.99 (1H, m, 2a1bOHH+), 1.62–1.53 (2H, m, 2a1bOHH+), 0.91 (3H, t, *J* = 7.5 Hz, 2a1bOHH+) ppm. Elemental analysis calcd. for C14H18N2O3 (%): C, 64.11; H, 6.92; N, 10.68. Found (%): C, 64.06; H, 6.68; N, 10.77. IR of **2a** polymorph (ATR, cm<sup>−</sup>1): 3017w, 2965m, 2935m, 2873m, 2752m, 2635m, 2072w, 1594s, 1576s, 1554s, 1501s, 1462s, 1428m, 1371vvs, 1346s, 1306m, 1288w, 1272w, 1254m, 1219w, 1205m, 1171s, 1151m, 1133m, 1111w, 1066s, 1041s, 988s, 967w, 953m, 890m, 861s, 810s, 782vvs, 761s, 747s, 661m, 626s, 592s, 547w, 526w, 499m, 478m, 469m, 439m. IR of **2b** polymorph (ATR, cm−1): 3232w, 3063m, 2963m, 2936m, 2868m, 1590m, 1553s, 1519s, 1503s, 1459s, 1427m, 1388s, 1367vs, 1340s, 1253w, 1219w, 1205m, 1170m, 1148m, 1068s, 1011w, 973w, 954w, 917w, 892m, 863s, 811s, 787vvs, 753m, 689m, 627s, 596s, 543w, 520m, 506m, 479w, 455w.

**(2a2m1pOHH)quin (3)**. Quinaldinic acid (100 mg, 0.58 mmol), methanol (10 mL), and 2-amino-2-methyl-1-propanol (108 μL) were added to an Erlenmeyer flask. The mixture was stirred until all the solid was consumed. The resulting solution was left to stand at ambient conditions. On the following day, it was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. Colorless crystals of (2a2m1pOHH)quin were filtered off. Yield: 111 mg, 73%. Notes. PXRD confirmed that the product is mostly **3b** polymorph (Figure S3). Single crystals of **3a** polymorph were obtained as follows. [Cu(quin)2(H2O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL), and 2-amino-2-methyl-1-propanol (0.5 mL) were added to an Erlenmeyer flask. The mixture was stirred thoroughly until all the solid was consumed. The resulting blue solution was left to stand at ambient conditions. On the following day, a mixture of colorless, needle-like crystals of **3a** polymorph and blue crystalline solid *syn*- [Cu2(quin)2(2a2m1pO)2] was obtained. Single crystals of **3b** polymorph were obtained as follows. Teflon container was filled with [Cu(quin)2(H2O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-amino-2-methyl-1-propanol (0.5 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 h at 105 ◦C. Afterwards, the reaction mixture was allowed to cool slowly to room temperature. The resulting blue solution was left to stand at ambient conditions. After a few days, a mixture of colorless, needle-like crystals of **3b** polymorph and blue crystalline solid *syn*-[Cu2(quin)2(2a2m1pO)2] was obtained. 1H NMR (500 MHz, DMSO-*d*<sup>6</sup> with 0.03% *v/v* TMS): δ 8.30 (1H, d, *J* = 8.4 Hz, quin−), 8.10 (1H, d, *J* = 8.5 Hz, quin−), 8.01 (1H, d, *J* = 8.4 Hz, quin−), 7.94 (1H, dd, *J* = 8.1, 1.4 Hz, quin−), 7.75–7.72 (1H, m, quin−), 7.60–7.57 (1H, m, quin−), 3.43 (s, 2H, 2a2m1pOHH+), 1.22 (s, 6H, 2a2m1pOHH+) ppm. Elemental analysis calcd. for C14H18N2O3 (%): C, 64.11; H, 6.92; N, 10.68. Found (%): C, 63.97; H, 6.64; N, 10.71. IR of **3a** polymorph (ATR, cm−1): 3185w, 2980m, 2894m, 2829s, 2724m, 2633m, 2593m, 2543m, 2168w, 1630s, 1578s, 1549vs, 1503m, 1482m, 1467s, 1426m, 1385vs, 1372vs, 1345s, 1327m, 1299m, 1264m, 1213w, 1173s, 1148m, 1114m, 1095m, 1067vs, 1009w, 980w, 958w, 946w, 912w, 893m, 873m, 853m, 804s, 778vvs, 752s, 737s, 697m, 651m, 630s, 592s, 551m, 523m, 480m, 459vvs, 421m. IR of **3b** polymorph (ATR, cm−1): 3173w, 3010m, 2987m, 2975m, 2910m, 2831m, 2683m, 2583m, 2499m, 1619s, 1544vs, 1502s, 1474m, 1458s, 1423m, 1384vs, 1371vs, 1349s, 1307m, 1274s, 1251s, 1211m, 1192m, 1173s, 1144m, 1108m, 1093s, 1067s, 1017w, 999w, 988w, 972w, 952m, 919w, 888m, 873s, 834m, 803s, 775vvs, 739vs, 640w, 627s, 594s, 552m, 522m, 492m, 475m, 453s.

**X-ray diffraction analysis.** Agilent SuperNova diffractometer (Agilent Technologies XRD Products, Oxfordshire, UK) with molybdenum (Mo-K*α*, *λ* = 0.71073 Å) micro-focus sealed X-ray source was used to obtain X-ray diffraction data on single crystal at 150 K. The diffractometer was equipped with mirror optics and an Atlas detector. The crystals were placed on a glass fiber tip with silicon grease, which was mounted on the goniometer head. CrysAlis PRO [27] was used for data processing. Structures were solved with Olex<sup>2</sup> software [28] using intrinsic phasing in ShelXT [29] and refined with the least squares method in ShelXL [30]. Anisotropic displacement parameters were determined for all non-hydrogen atoms. With the exception of **2b**, NH3 <sup>+</sup> and OH hydrogen atoms of protonated amino alcohols were located from a difference Fourier map and refined with isotropic displacement parameters. Owing to the residual density in **2b**, the hydrogen atoms of NH3 + moiety were added in calculated positions. The residual density, i.e., a 2.30 e−/Å3 peak on a special position with too-short contacts to adjacent atoms, could not be interpreted. The data set, obtained from a crystal from a different batch, revealed the same problem. The remaining hydrogen atoms were placed in geometrically calculated positions in all structures and refined using riding models. Crystal structure analysis was performed with the program Platon [31], while the figures were made with Mercury [32]. The crystallographic data are summarized in Table 4. All crystal structures were deposited to the Cambridge Crystallographic Data Center (CCDC) and were assigned deposition numbers 2100261 (**1**), 2100262 (**2a**), 2100263 (**2b**), 2100264 (**3a**), and 2100265 (**3b**). These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html (accessed on 15 October 2021) (or from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44 1223 336033; E-mail: deposit@ccdc.cam.ac.uk).

**Table 4.** Crystallographic data for **1**–**3b**.

