Synthesis, photoluminescent, antibacterial activities and theoretical studies of 4-hydroxycoumarin derivatives

• Two novel biscoumarin and epoxydicoumarin derivatives (DBH and DDT) have been synthesized successfully.
• The crystal structure of DBH was determined using X-ray diffraction.
• The two compounds exhibit strong blue emissions under ultraviolet light excitation.
• Between the two compounds, DBH showed the better potent antibacterial activity.

Two new biscoumarin and epoxydicoumarin derivatives, namely, 3,3′-(4-di-p-tolyl-amino-benzylidene)-bis-(4-hydroxycoumarin) (DBH) and 9-(4-di-p-tolyl-amino-phenyl)-1,8-dioxo-9H-dibenzo[c,h]-2,7,10-trioxanthene (DDT), were synthesized and characterized via IR, 1H NMR, HRMS, single crystal X-ray crystallography and UV–vis absorption spectra. The fluorescence behaviors of DBH and DDT in dichloromethane solutions were observed. The in vitro antibacterial activity of DBH and DDT against Staphylococcus aureus (S. aureus ATCC 29213), methicillin-resistant S. aureus (MRSA XJ 75302), vancomycin-intermediate S. aureus (Mu50 ATCC 700699), and USA 300 (Los Angeles County clone, LAC) was evaluated by observing the minimum inhibitory concentration. The results showed that compared with compound DDT, DBH exhibited better potent antibacterial activity.