Synthesis, Characterization of New Benzopyran Pyrimidines and Study of their Solvatochromic Behaviour

Five new benzopyran pyrimidines (5a-e) were synthesized in three steps by using silica-sulphuric acid as catalyst. All the synthesized benzopyran pyrimidines with various substituents were characterized by spectroscopic techniques such as 1H NMR, 13C NMR, IR and mass spectroscopy. The structural features of these molecules containing pyrimidine ring with π-conjugated systems and various functional groups on the aromatic rings greatly influence their photophysical properties. Thus, they behave as better candidates for developing the photoelectric materials. Thus, it is proposed to synthesize, characterize and study their solvatochromic behaviour in various polar and non-polar organic solvents viz. dichloromethane, tetrahydrofuran, ethyl acetate, acetonitile and ethanol. Interestingly, all the target molecules exhibited greater Stoke’s shift (λf-λa) in dichloromethane except for compound 5e, which exhibited greater value in tetrahydrofuran, possibly due to the moderately polar nature of the solvent. The synthesized benzopyran pyrimidines displayed solvatochromic characteristics due to the presence of multiple substituted functional groups on the rings in different organic solvents. Due to their remarkable properties, they could serve as potential candidate molecules for future investigations into photoelectric materials.