1,2,3-triazoles as conjugative π-linkers in push-pull chromophores:: Importance of substituent positioning on intramolecular charge-transfer

Isomeric charge-transfer chromophores using 1,2,3-triazol-diyl as linker have been studied experimentally and computationally. The instability of the polarized reactants precluded the use of the Huisgen reaction and alternative synthetic methodologies were employed. Charge-transfer absorptions between an N,N-dimethylanilino and a dicyanovinyl group are modest to strong, with maxima from lambda(max) = 400 to 453 nm depending on substituent positioning. TD-B3LYP/6-31G(d) calculations are within 0.6 eV of experiment and assign these bands as HOMO-LUMO transitions.