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From time immemorial, technicians in the basic sciences have searched for methods of analysis that require a minimum of sample and sample preparation and that involve the least amount of destruction of the sample while obtaining the maximum information from it. The laser microprobe goes a long way toward meeting these elusive standards of performance in microspectroscopy.

Three kinds of 4-hydroxycoumarin derivatives, namely, biscoumarins (1–4), epoxydicoumarins (5–8) and dihydropyrans (9–12), were synthesized and the antibacterial activity of each of them was evaluated. The result of preliminary bioassay shows that the lowest minimal inhibitory concentration (MIC) of compounds 1 and 2 against drug-sensitive S. aureus(ATCC 29213) and methicillin-resistant S. aureus(MRSA XJ 75302, Mu50, ATCC 700699 and USA 300) is 4–64 ug/mL. Additionally, there are two classical intramolecular O—H⋯O hydrogen bonds (HBs) in the structures of biscoumarins (1–4), and their corresponding HB energies were further calculated by the density functional theory (DFT) [B3LYP/6-31G*] method.