Spectroscopic studies on [(DD18C6H 2)(HPA) 2](PA) 2 and [(DD18C6H 2)(DDQ) 2](DDQH) 2 formed in the reaction of N, N′-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane with HPA and DDQ

The interaction of the mixed oxygen–nitrogen cyclic base, N, N′-dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane (DD18C6) with π-acceptors such as picric acid (HPA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) has been studied spectrophotometrically in chloroform at 25 °C. The results obtained indicate the formation of 1:4 charge–transfer complexes with the general formula (DD18C6)(acceptor) 4. The electronic and infrared spectra of charge–transfer complexes along with the 1H NMR spectra were recorded and discussed. Based on the data obtained, the complexes were formulated as [(DD18C6H 2)(HPA) 2](PA) 2 and [(DD18C6H 2)(DDQ) 2](DDQH) 2. A general mechanism explaining the formation of the DDQ complex has been suggested.