10.1021/ic2015226
The research focuses on the synthesis, structural characterization, and photophysical properties of a series of Cu4I4 clusters supported by P∧N-type ligands. The clusters, designated as 1?5, were synthesized using 2-[(diRphosphino)methyl]pyridine ligands with different organic groups (R = phenyl, cyclohexyl, tert-butyl, iso-propyl, ethyl) attached to the phosphine moiety. These clusters exhibit a rare “octahedral” geometry, differing significantly from the commonly reported “cubane” and “stairstep” geometries. The central core consists of copper atoms arranged in a parallelogram with μ4-iodides above and below the copper plane, and the P∧N ligands bridge the long edges in an antiparallel fashion. The photophysical studies reveal that the emission color of these clusters can be tuned from blue to white by altering the organic groups on the phosphine moiety. The luminescence spectra of clusters 3 and 4 display a single emission around 460 nm at room temperature, assigned to a triplet halide-to-ligand charge-transfer (3XLCT) excited state, while clusters 1, 2, and 5 also have a second band around 570 nm, assigned to a Cu4I4 cluster-centered (3CC) excited state. The research also includes the synthesis of P∧N-type ligands from 2-picoline and chlorodiorganophosphines, and the structural and photophysical properties of a dinuclear Cu2I2(P∧N)2 complex obtained during the sublimation of cluster 3.
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