A Strong Donor–Acceptor System Based on a Metal Chalcogenide Cluster and Porphyrin

Although great progress has been made for charge transfer (CT) compounds of various organic donor–acceptor systems, no CT compounds containing both inorganic chalcogenide cluster anions and organic porphyrin cations have been reported. Herein, a germanium chalcogenide cluster (Ge₄S₁₀^4–) is chosen as an electron donor and a methylated tetrakis­(4-pyridyl)­porphyrin (5,10,15,20-tetrakis­(N-methyl-4-pyridyl)­porphyrin, TMPyP) is selected as an electron acceptor to create chalcogenide cluster–porphyrin CT compounds (TMPyP-Ge₄S₁₀)·5H₂O (1) and (MnTMPyP-Ge₄S₁₀)·13H₂O (2). Their crystal structures have been characterized by single-crystal X-ray diffraction. Compound 1 is an ionic CT salt assembled through interion interactions, and compound 2 is a neutral CT dyad formed by metal–ligand axial coordination of the chalcogenide cluster with manganese porphyrin. The strong charge transfer properties are revealed by electronic spectra, theoretical calculations, ¹H NMR, and ESR. The CT intensity of the chalcogenide cluster–porphyrin system can be modulated by metalation. The fluorescence and photocurrent response properties of 1 and 2 are related to the CT intensity.