Luminescence Behavior of Cationic and Neutral CuI Complexes of Phosphine and Pyridine Embedded 1,2,3-Triazole

Synthesis of a potentially polydentate, phosphine and pyridine embedded 1,2,3-triazole, o-Ph2P(C6H4)C(CH)-1,2,3-N-3(CH2)(Py) (<bold>1</bold>) (here onward referred to as "(PN3N)-N-boolean AND-N-boolean AND") and its copper complexes are described. Reactions of <bold>1</bold> with CuX yielded mononuclear [Cu{((PN3N)-N-boolean AND-N-boolean AND)(2)-kappa(2)-P,N}]X (<bold>2</bold> - <bold>4</bold>; X = I, CuBr2 and CuCl2) and dinuclear [Cu-2{((PN3N)-N-boolean AND-N-boolean AND)(2)-kappa(4)-P,N,N,N}]X (<bold>5</bold> X = OTf, <bold>6</bold> X = BF4) complexes. Interestingly, the cationic complex [Cu{((PN3N)-N-boolean AND-N-boolean AND)(2)-kappa(2)-P,N}]I (<bold>2</bold>) in acetonitrile changes into neutral complex [Cu-3(mu(2)-I)(2)(mu(3)-I)(NCCH3){((PN3N)-N-boolean AND-N-boolean AND)-kappa(4)(mu(2)-P,N)(mu(2)-N,N)}](<bold>7</bold>), which on addition of dichloromethane reverts back to the cationic form. The photoluminescent characteristics of cationic complexes are significantly impacted by the nature of counteranions and hence the corresponding photoluminescence quantum yields. Cationic complex <bold>2</bold> showed an increase in quantum yield and lifetime on changing over to neutral complex <bold>7</bold>. TD-DFT calculations also assisted in assessing the photophysical properties.