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Study of the thermal behavior were performed for the first time for a series of ligand‐to‐ligand charge transfer complexes of "α‐diimine‐NiII‐catecholate" type: NiII(3,6‐Cat)(bipy) (1), NiII(3,6‐Cat)(bipytBu) (2) and NiII(3,6‐Cat)(DADdipp) (3), where 3,6‐Cat is 3,6‐di‐tert‐butyl‐catecholate, bipy and bipytBu are 2,2′‐bipyridine and its 4,4′‐di‐tert‐butyl‐substituted analog, DADdipp is 1,4‐bis(2,6‐di‐iso‐propylphenyl)‐1,4‐diaza‐1,3‐butadiene. The phase transition behavior, vapor phase composition, volatility, and thermodynamics of the sublimation process (enthalpy and entropy calculations) of chromophores 1–3 were examined using DSC, TGA, EI‐MS, and the Knudsen effusion method with weight registration of the sublimated substance. The Hirshfeld surface analysis was implemented to establish a relationship between the characteristics of the crystal packing, and the thermal properties. The compounds 1–3 are distinguished by the high thermal stability and good volatility, as well as the completeness of the transition to the gas phase under low pressure conditions. An increase in ligand's bulkiness leads to a "rarefaction" of the crystal packing of the chromophore, and a corresponding rise of volatility in the order 1≤2<3. [ABSTRACT FROM AUTHOR]

The thermal properties and an opportunity for photovoltaic applications were studied for a series of transition metal complexes derived on functionalized o‐aminophenols ‐ mixed‐valent CoIII compounds and bis‐o‐iminobenzosemiquinonato NiII complexes. TGA and DSC explored the thermal behavior of compounds in the solid state. EI‐MS established the vapor phase composition. The temperature dependences of a saturated vapor pressure were measured by the Knudsen effusion method with the weight registration of the sublimated substance. Based on the volatility study data, the thermodynamic parameters of a sublimation process were calculated. A high absorptivity distinguishes metal complexes under investigation at visible and NIR regions (i. e., vis/NIR dyes) and, thus, were tested as photosensitizers in the fabricated dye‐sensitized solar cells. The photoelectric conversion efficiency (PCE) was estimated for devices with the NiII derivatives. The CoIII complexes demonstrated the absence of photovoltaic potential. [ABSTRACT FROM AUTHOR]