Spectroscopic characterization of molecular interactions between DNQ-PACs and phenolic resins using selectively nitrogen-15 labeled DNQs

摘要

Abstract: Interactions between diazonaphthoquinone (DNQ)-photoactive compounds (PACs) and phenolic resins with different degrees of ortho, ortho-bonding have been investigated using solid state nitrogen-15 nuclear magnetic resonance (NMR) and vibrational (infrared and Raman) spectroscopic techniques. A specifically nitrogen-15 labeled PAC was synthesized to facilitate solid state nitrogen-15 NMR experimentation, and to resolve ambiguities in vibrational spectra. Comparison of vibrational spectra of the $+15$/N-labeled PAC and its natural abundance $+14$/N analog showed conclusively that Fermi resonance as well as hydrogen-boding resin-PAC interactions influence changes in the out-of-phase diazo stretching region near 2100 cm$+$MIN@1$/. Solid state nitrogen-15 NMR of the $+15$/N-labeled PAC in poly(p-hydroxystyrene), in a m-cresol 3,5-xylenol novolak, and in a mainly m,p- cresol novolak showed the binding situation in the resins to be diffuse, but quite similar. Although the three resins examined are lithographically very different, the observed nitrogen- 15 shifts were small compared to the broadening of the resonances, and did not show major differences due to ortho, ortho-bonding effects. !10