No abstract

No abstract

A new class of porphyrazine macrocycles carrying peripheral diazepine rings, i.e. tetrakis‐2,3‐(5,7‐diphenyl‐6H‐1,4‐diazepino)porphyrazine [Ph2DzPzH2](H2O)4, and its metal derivatives of formula [Ph2DzPzM](H2O)x=2–7 [M = MgII(H2O), CuII, ZnII] have been prepared and characterized. Single crystal X‐ray work on the monomeric precursor 5,7‐diphenyl‐2,3‐dicyano‐6H‐1,4‐diazepine, Ph2(CN)2Dz, and NMR spectra (CDCl3, (CD3)2SO) and UV/Vis spectra in solution of different media (basic, neutral, acid) of the monomer and its macrocyclic derivatives have provided information on the conformational flexibility of the diazepine ring as well as on the structural and electronic features of the entire porphyrazine skeleton.

We report extensive structural and spectroscopic characterization of four mixed stack chargetransfer (ms-CT) crystals formed by the electron donor 3,3',5,5'-tetramethylbenzidine (TMB) with Chloranil (CA), Bromanil (BA), 2,5-difluoro-tetracyanoquinodimethane (TCNQF2) and tetrafluorotetracyanoquinodimethane (TCNQF4). Together with the separately studied TMB-TCNQ [Phys. Rev. B 95, 024101 (2017)] the TMB-acceptor series span a wide range of degree of CT, from about 0.14 to 0.91, crossing the neutral-ionic interface, yet retaining similar packing and donor-acceptor CT integrals. First principle calculations of key phenomenological parameters allows us to get insight into the factors determining the degree of CT and other relevant physical properties.

New pentanuclear porphyrazine complexes of formula [{Pd­(CBT)2}4LM]·xH2O (L = tetrakis-2,3-[5,6-di­(2-pyridyl)­pyrazino]­porphyrazinato anion, CBT = m-carborane-1-thiolate, and M = MgII(H2O), ZnII, PdII) were prepared in good yield as dark green hydrated amorphous solids by reaction of the respective pentanuclear species [(PdCl2)4LM] with m-carboran-1-thiol in CH3CN. Physicochemical characterization of the new species was carried out by elemental and thermogravimetric analysis along with IR and 1H/13C NMR measurements. UV–vis spectral characterization performed in DMSO, DMF, and pyridine solution provided information about the stability of the new homo/heteropentanuclear species and their tendency to undergo detachment of the peripheral Pd­(CBT)2 groups. The data from NMR, UV–vis, and electrochemical experiments indicate that external coordination of the Pd­(CBT)2 units to the mononuclear [LM] species affects only slightly the π electron distribution within the internal macrocyclic choromophore. The Pd­(CBT)2 units are released in pyridine solution and in the case of the ZnII complex [{Pd­(CBT)2}4LZn] give rise to a finely crystalline light-yellow solid identified by single-crystal X-ray work as the trans isomer of the bispyridine adduct [py2(CBT)2Pd]. The new pentanuclear macrocyclic complexes behave in DMF solution as active photosensitizers for singlet oxygen production, 1O2, the cytotoxic agent in anticancer photodynamic therapy, and have larger quantum yield values (ΦΔ = 0.6–0.7) than those found on average for the related tetrapyrazinoporphyrazine analogs (ΦΔ = 0.4–0.6). The presence of the CBT groups in the currently investigated complexes opens up the possibility for their use in boron neutron capture therapy, leading potentially to new bimodal anticancer curative drugs.