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The autocyclotetramerization of the precursor 2,3-dicyano-5,6-di(2′-pyridyl)pyrazine [(CN)2Py2Pyz] in the presence of MCl3compounds (M = AlIII, GaIII) leads to the formation of the new mononuclear porphyrazine complexes [Py8TPyzPzMCl]·xH2O (Py8TPyzPz = tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazinato anion). From these species, the hydroxide analogues [Py8TPyzPzMOH]·xH2O were obtained by contact with hot water, and their corresponding pentanuclear species [(PdCl2)4Py8TPyzPzMCl]·xH2O could be easily formed by the reaction with PdCl2. Physicochemical characterization of the mono- and pentanuclear macrocycles was based on elemental analysis, and mass, powder X-ray, and IR spectra. UV–vis spectral studies of the mononuclear species in solutions of DMF, DMSO, or pyridine (c≈ 10–5–10–6M) indicate (mainly in DMF and DMSO) the initial presence of aggregation, in some cases accompanied by the concomitant occurrence for the complex of a one-electron reduction. While disaggregation into a single species evolves spontaneously over time, the −1 charged species, eventually also found present, can be brought back to its neutral form by addition of a slight amount of HCl, the final spectrum showing the presence of the starting neutral species in its pure monomeric form. Similar aspects were faced also for the parent pentanuclear complexes. Cyclic voltammetry experiments, conducted for the mono-/pentanuclear complexes in DMF and DMSO (c≈ 10–4M), exhibit progressive one-electron reductions (1 → 4) characterized by E1/2values (V vs SCE) positioned to significantly less negative values than those known for the phthalocyanine (Pc) analogues, these data confirming the previously already proven higher electron-deficient character of the MIIderivatives of the Py8TPyzPz macrocycle with respect to Pc. The role of the present new series of AlIIIand GaIIImacrocyclic species to act as photosensitizers for the generation of singlet oxygen, 1O2, the cytotoxic agent in the anticancer treatment known as photodynamic therapy (PDT), has been explored in DMF/HCl. Among the quantum yields ΦΔ, the value found for the GaIIIcomplex [Py8TPyzPzGaCl] (0.68), practically coincident with that observed for the TTDPz analogue (0.69), is well above those of most porphyrazines analogues (ΦΔ= 0.4–0.6), a result encouraging further research work for potential applications in the biochemical field.

The chloroiron(III) complex of 2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,10-diazaporphyrin, [(Cl)FeMBDAP], was prepared and studied by X-ray crystallography and by solution 1H NMR and UV−vis measurements. In the crystal structure of hemisolvate [(Cl)FeMBDAP] × 0.5CHCl3, two nonequivalent [(Cl)FeMBDAP] units containing Fe1 and Fe2 are arranged in π-dimers with considerable overlap on their concave sides. Axial chloride bonded to Fe2 is solvated by hydrogen bonding with CHCl3. Parameters of the coordination pyramid have typical values for the spin-mixed (S= 3/2 ÷ 5/2) FeIIIcomplexes in the case of Fe1 and are characteristic for the pure intermediate-spin state for Fe2 (displacement from the (NPyr)4planes − 0.385 and 0.290 Å and the average NPyr−Fe bond lengths −1.992 and 1.954 Å for Fe1 and Fe2, respectively). Effective magnetic moments in CHCl3and CH2Cl2capable of specific solvation of chloride by hydrogen bonding (4.5−4.6 μBat 298 K) are indicative about mixed intermediate/high-spin state S= 3/2 ÷ 5/2, with the S= 3/2 contribution increasing upon lowering of the temperature (4.02 μBin CD2Cl2at 193 K). In nonsolvating CCl4, C6D6, and THF-d8, the μeffvalues are consistent with the predominantly high-spin state at ambient temperature (5.5−5.75 μBat 298 K) and almost pure S= 5/2 state at low temperature (ca. 5.9 μBin THF-d8below 270 K). Downfield isotropic shifts from 35 to 50 ppm are observed for α-alkyl protons and upfield shifts from −5 to −15 ppm for meso-CH protons, which is characteristic for the presence of the intermediate-spin state. The splitting of signals of the diastereotopic α-CH2protons is increased with growth of the S= 3/2 state contribution from 1.5 to 4 ppm in nonsolvating to 11 ppm in specifically solvating solvents at 298 K and further to 31 ppm at 193 K (in CD2Cl2). In the presence of DMSO addition and in methanol solution, the single CH2signal is observed at 25−28 ppm, and the meso-CH resonance is also shifted downfield to ca. 30 ppm, indicating the formation of six-coordinated complexes [(DMSO)2FeMBDAP]+and [(MeOH)2FeMBDAP]+, the latter having the μeffvalue of 4.92 μBat 291 K is a spin-mixed species. The electron spin resonance spectra recorded at 77 K indicates that in frozen glasses in CD2Cl2and THF molecules in the high-spin state (g⊥∼ 6) and the predominantly intermediate-spin state (g⊥∼ 4.2−4.3) coexist together.

Mixed cyclization of 5,7‐diphenyl‐6H‐1,4‐diazepine 2,3‐dicarbonitrile and tetrafluorophthalonitrile in the presence of boron trichloride affords along with symmetrical perfluorinated subphthakocyanine, [F12sPc], two novel subporphyrazine‐type products which were isolated by column chromatography and characterized by mass‐sprectometry, NMR, IR, UV‐VIS and fluorescent spectroscopy. It was established that co‐cyclomerization of dinitriles is accompanied by electrophilic chlorination of 1,4‐diazepine ring by evolved Cl2resulting in formation of dibenzosubporphyrazine [F8sPc1] with fused 6‐chloro‐5,7‐diphenyl‐6H‐1,4‐diazepine fragment. According to DFT modelling and 1H NMR data, a more stable diastereomer with an axial Cl atom is formed and no inversion of the 1,4‐diazepine ring is observed. Hydrolytic cleavage of the 1,4‐diazepine fragment in [F8sPc1] is observed upon chromatography or in the presence of a strong acid (CF3COOH) and leads to 2‐amino‐3‐benzamide substituted dibenzo subporphyrazine [F8sPc2]. Fluorescence of [F8sPc1] (ΦF=0.03) is ca 10 times lower than for [F12sPc] (ΦF=0.28) due to the combined effect of intramolecular charge transfer (ICT) from the donor diazepine ring to the acceptor sPc macrocycle and heavy atom effect of chlorine. Fluorescence of [F8sPc2] is almost completely quenched by ICT from −NH2group to the electron‐deficient subporphyrazine core (ΦF<0.001), but addition of acid leads to protonation of the amino group and switch‐ON the fluorescence. Therefore, aminobenzamide substituted subporphyrazines can be considered as perspective pH‐sensitive fluorophores. 1,4‐Diazepine ring in novel low‐symmetry subphthalocyanine analog is easily chlorinated and its hydrolytic cleavage leads to aminobenzamide derivative with switchable fluorescent properties.

Archetypal photovoltaic cells are fabricated in order to elucidate the effect of a metal embedded in a semitransparent trilayer electrode on photovoltage. A series of electrodes are formed by thermal deposition of MoOx, metal and MoOxlayers, in said succession (MoOx= substoichometric molybdenum trioxide, metal = Au, Cu, Ag, Al, In, Mg, Yb). The parameters of the Schottky‐type cells consisting of thus made bottom anode, a subphthalocyanine boron chloride (SubPc) photoabsorber and a bilayer LiF/Al top cathode are measured and compared to those of the reference cell with an ITO/MoOxanode. Photovoltage does not correlate with the work function of a metal in the anode, while the photocurrent is inversely proportional to the anode sheet resistance. The highest efficiency is achieved with the silver interlayer, but the reference cell with ITO outperforms any cell with a trilayer anode. Then, comparison is made with a series of cells, in which the metal (Cr, Ni, Ag, Al, and Ta) in anode is deposited by a dc magnetron sputtering. In these cells, the photovoltage rises monotonically with the metal work function. Magnetron sputtered nickel in the anode provides the best cell performance, closely approaching that of the reference cell. The effect of the metal in the semitransparent composite bottom anode on the performance of the organic photovoltaic cells with a subphthalocyanine photoabsorber is studied. Correlations between the work function of a metal in the anode and the photovoltaic parameters of cells are traced.

A hybrid inorganic/organic heterojunction formed by p‐type cuprous iodide CuI and n‐type fullerene C60was employed in the archetypal photovoltaic devices. The thickness of the p‐CuI layer deposited on a molybdenum oxide (MoOx) anode buffer was optimized to achieve a higher efficiency, while the thickness of the n‐C60photoabsorber layer was fixed. In an attempt to obtain semitransparent devices, a trilayer MoOx/metal/MoOxcathode with a BCP underlayer was applied (metal = Ag or Mg, BCP = bathocuproine). The maximum photovoltage of such devices on a PET/ITO substrate was equal to 0.75 V for an average transparency of about 35% over the range of 380–1000 nm. Similar devices having a non‐transparent Al cathode in conjunction with an Alq3 underlayer generate photovoltage of 0.82 V (Alq3 = tris‐8‐hydroxy­quinolinato‐aluminum), which shows the important effect of hybrid junctions in multilayer organic‐based devices.