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A series of triads, consisting of a triarylamine electron donor and a perylene diimide electron acceptor which were attached to two different wings of a triptycene bridging unit, was investigated concerning the dynamics of photoinduced charge separation and charge recombination processes with a particular focus on the involved spin-chemical aspects. Attaching electron-donating or electron-withdrawing substituents to the third wing of the triptycene bridge allowed tuning the electron transfer processes. These processes were investigated via fs-transient absorption spectroscopy and ns-transient absorption spectroscopy in an external magnetic field. The resulting magnetic field-dependent decay dynamics were analysed and modelled using the stochastic Liouville equation which yielded rate constants for the charge recombination and the exchange energy. In combination with a diabatic rate theory and Anderson's perturbative treatment of the exchange energy, these data gave a complete set of rate constants for charge separation and charge recombination from which the diverse electronic couplings between the involved states were derived. These couplings depend linearly on the inverse energy of virtual triptycene bridge states which allows tuning the electron transfer dynamics by modifying the triptycene bridge.

Exact analysis of spin crossover in infinite elastic chain of two-spin exchange clusters was performed theoretically beyond mean-field approximation. Statistical mechanics of the system was exactly calculated by means of the transfer matrix technique. A possibility of spin-Peierls-like magneto-structural transition in a one-dimensional chain was shown as a result of interrelation of spin and elastic subsystems of the chain. The importance of the boundary conditions for spin crossover to occur was shown. The smoothness of spin crossover depends on the parameters of chain elasticity and the crossover position on the temperature scale is defined by the dependence of exchange integral on the cluster deformation. The proposed model qualitatively describes the main scenario of spin crossover effect in the chain polymer heterospin complex of copper(ii) hexafluoroacetylacetonate with methyl pyrazol-substituted nitronyl nitroxide containing two-spin exchange clusters.