The electronic absorption and f luorescence emission spectra of the ROR′-DADQs in chlorof orm solution and microcrystalline solid state are collected in Figure . All the solutions show absorption with max ~ 415-420 nm (Figure ) indicating the similarity of the f luorophore units; these absorptions arise f rom the intramolecular charge transf er of the DADQ zwitterionic structure. The electronic transitions show slight blue shif t in the crystalline state, to 375-385 nm and 365-375 nm in RO2-DADQs and RO3-DADQs respectively (Figure ). The f luorescence spectra show more prominent blue shif ts f rom λmax ~ 500 nm in solution (Figure ) to λmax ~ 450-470 nm and ~ 437-445 nm in microcrystalline solid RO2-DADQ and RO3-DADQ respectively (Figure ); the emission peak shif ts are displayed graphically in Figure . The f luorescence excitation spectra (Figure ) match closely the electronic absorption spectra suggesting that the emission occurs f rom the electronic state to which the direct absorption takes place. The blue shif t of the spectra f rom the Please do not adjust margins Please do not adjust margins solution to the solid state is typical of DADQs and arises f rom the local f ields due to the neighboring dipolar molecules. The notable larger shif ts in RO3-DADQs compared to RO2-DADQs are indicative of the more ef f icient supramolecular packing in the crystals of the f ormer and the consequent stronger local f iled eff ects. Equally signif icant as the blue shif ts are the enhancement of the f luorescence emission quantum yields f rom the solution to the microcrystalline solid state; the values and the f luorescence ef f iciency enhancement (FEE) f actor f or all the compounds are collected in Table . The phenomenon of f luorescence enhancement, of ten called aggregation-induced emission, arises due to multiple f actors including the restriction of intramolecular motions in the rigidif ied molecular environment and the consequent blockage of non-radiative excited state relaxation pathways , as well as f avorable intermolecular orientations hindering energy transf er channels that otherwise would lead to f luorescence quenching. The FEE of RO2-DADQs (12 -84) is relatively lower than that of RO3-DADQs (92 -211) (Table ), once again pointing to the more compact supramolecular organization in the latter. The spectroscopic results reveal common trends observed within the two series of ROR′-DADQs in terms of the optical absorption, f luorescence emission (Figure ) and FEE.