*3.4. Deposition of Porphyrazines on TiO<sup>2</sup> P25 Nanoparticles*

Studied porphyrazines were deposited on P25 Aeroxide®® titanium(IV) oxide (TiO2) nanoparticles using the chemical deposition method [50]. In general, porphyrazine **4** or **5** in the amount of 5 mg was added to a dispersion of 100 mg P25 nanoparticles (sized approx. 21 nm) in 20 mL of dichloromethane:methanol mixture (1:1, *v*/*v*). After the reaction mixture had been stirred for 72 h, the solvents were evaporated on a rotary evaporator. Next, the obtained hybrid material was air dried for 24 h. The ratio of the macrocycle to the P25 TiO<sup>2</sup> was 1:20 (*w*/*w*).

The hybrid materials were subjected to nanoparticle size measurements using a Malvern Panalytical NanoSight LM10 instrument (Malvern, UK), equipped with sCMOS camera, and 405 nm laser. The data acquisition and storage were provided by Nanoparticle Tracking Analysis (NTA) 3.2 Dev Build 3.2.16 software (Malvern, UK). Throughout, the nanoparticles' dispersions were diluted with water (1 mg in 1 mL) to obtain the operating range of nanoparticle concentration. The measurements were performed at 25.0 ± 0.1 ◦C, and at the syringe pump infusion rate set to 100 µL/min.

## *3.5. Photocatalytic Studies*

The photocatalytic studies were performed using a red-light LED lamp (EcoEnergy, Gda ´nsk, Poland) at wavelength 665 nm, and a power adjusted to 10 mW/cm<sup>2</sup> with the use of an Optel radiometer. The measurements were conducted in a 10 mm quartz cuvette in *N*,*N*′ -dimethylformamide (DMF). In the experiments with a reference standard 1,3-diphenylisobenzofurane (DPBF), 1 mL of 0.1 mM DPBF solution in DMF was mixed with 1 mL of TiO<sup>2</sup> dispersion in DMF (0.1 mg/mL). In the experiments with active pharmaceutical ingredients (diclofenac sodium salt and ibuprofen), DPBF was replaced by 1 mL of 0.3 mM diclofenac sodium salt solution in DMF or 1 mL of 1.5 mM ibuprofen solution in DMF. The irradiations of mixtures were performed with an LED lamp within 8 min. The UV–Vis spectra were recorded every 2 min on an Ocean Optics USB 2000+ spectrometer (Ocean Optics Inc., Largo, FL, USA).

#### **4. Conclusions**

Two novel sulfanyl magnesium(II) and zinc(II) porphyrazines with morpholinylethyl periphery were synthesized in the cyclotetramerization reaction using a dimercaptomaleonitrile derivative. The obtained macrocyclic compounds were broadly characterized by ESI MS spectrometry, 1D and 2D NMR techniques, and UV–Vis spectroscopy. Both porphyrazines were subjected to electrochemical studies. Subsequently, the obtained porphyrazines were embedded on titanium(IV) oxide nanoparticles' surface and characterized in terms of particle size and distribution. The obtained hybrid materials' applicability was assessed in photocatalytic studies with a singlet oxygen quencher (DPBF) and selected drug active pharmaceutical ingredients (diclofenac sodium salt and ibuprofen). In the UV–Vis and NMR studies, the characteristic features of porphyrazines were confirmed. The electrochemical studies revealed four irreversible redox processes for both porphyrazines. In addition, the calculated electrochemical band gap values were found to be in agreement with the optical ones. Interestingly, the obtained hybrid materials presented four times higher particle sizes compared with unmodified titanium(IV) oxide P25 nanoparticles and were monodispersive. The **4**@P25 material was found to be the most active in comparative photocatalytic tests with 1,3-diphenylisobenzofurane, and it was therefore used in the photooxidation studies of diclofenac sodium salt and ibuprofen. The **4**@P25 material revealed good photocatalytic potential. For this reason, it can be considered in future photocatalytic experiments with various organic compounds and active pharmaceutical ingredients as a potential hybrid material for the photodegradation of various organic pollutants.

**Supplementary Materials:** The following are available online: Figure S1. <sup>1</sup>H NMR spectrum of **4** in pyridine-*d*<sup>5</sup> . # indicates solvent residual peaks. Figure S2. <sup>13</sup>C NMR spectrum of **4** in pyridine-*d*<sup>5</sup> . # indicates solvent residual peaks. Figure S3. <sup>1</sup>H-1H COSY NMR spectrum of **4** in pyridine-*d*<sup>5</sup> . Figure S4. <sup>1</sup>H NMR spectrum of **5** in pyridine-*d*<sup>5</sup> . \* indicates solvent residual peaks and # stands for water residual. Figure S5. <sup>13</sup>C NMR spectrum of **5** in pyridine-*d*<sup>5</sup> . \* indicates solvent residual peaks. Figure S6. <sup>1</sup>H-1H COSY NMR spectrum of **5** in pyridine-*d*<sup>5</sup> .

**Author Contributions:** Conceptualization, T.K.; methodology, T.K.; investigation, T.K., W.S. and A.T.; writing—original draft preparation, T.K.; writing—review and editing, W.S. and T.G.; visualization, A.T.; supervision, T.G.; funding acquisition, T.G. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Science Centre, Poland under Grant No. 2016/21/B/ NZ9/00783.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** This study was supported by the National Science Centre, Poland under Grant No. 2016/21/B/NZ9/00783 and the European Fund Regional Development Fund No. UDA-POIG.02.01.00-30-182/09. The authors thank Beata Kwiatkowska and Rita Kuba for excellent technical assistance.

**Conflicts of Interest:** The authors declare no conflict of interest

**Sample Availability:** Samples of the compounds **3**, **4**, and **5** are available from the authors.

#### **References**

