Bis-(1-(2-aminoethyl) piperidino), (2-(2aminoethyl) pyridino) and (1-(2-aminoethyl) pyrrolidino)-substituted dicyanoquinodimethanes: consequences of flexible ethylene spacers with heterocyclic moieties and amine functionalities

Heterocyclic building blocks possessing ethylene spacer and amine functionality such as 1-(2-aminoethyl) piperidine (1,2-AEPi), 2-(2-aminoethyl) pyridine (2,2-AEPy) and 1-(2-aminoethyl) pyrrolidine (1,2-AEPr) were reacted with tetracyanoquinodimethane (TCNQ) to give disubstituted compounds namely bis-(1( 2-aminoethyl) piperidino) dicyanoquinodimethane (1), bis-(2-(2-aminoethyl)-pyridino) dicyanoquinodimethane (2) and bis-(1-(2-aminoethyl) pyrrolidino) dicyanoquinodimethane (3). Utilization of 1,2-AEPi, 2,2-AEPy and 1,2-AEPr as disubstituents on TCNQ has resulted in interesting crystal structures. Inter-and intramolecular hydrogen-bond mediated and expanded supramolecular structures were observed in the lattices of the crystals. Strong fluorescence was observed in solids and solutions. (2) showed a strong second harmonic generation (SHG) whereas (1) and (3) were found to be SHG inactive. All compounds possess good thermal stabilities.