Spectral, crystal structure, thermal and antimicrobial characterisation of an organic charge transfer complex-3,5-dimethylpyrrazolinium picrate

A novel organic charge transfer complex, 3,5-dimethylpyrrazolinium picrate was grown and crystallized by slow evaporation solution growth method at room temperature. The absorption of the grown crystal was studied using UV–visible spectral analysis and observed that the crystal possesses minimum absorption between 250 and 900 nm. The lower cut-off wavelength and the optical transmittance window were identified by optical transmittance study. The emission spectrum of the complex shows peaks at 505 and 758 nm are due to the green and red fluorescence emissions respectively. The thermogravimetry–differential thermal analyses (TG–DTA) were used to investigate the thermal stability of the complex. The single crystal X-ray diffraction method indicates that the complex crystallizes in monoclinic system with space group P2(1)/C. The FTIR and polarised Raman spectra were used to confirm the presence of various functional groups. The different kinds of protons and carbons were assigned through NMR (1H and 13C) spectroscopic techniques. The nonlinear optical property (NLO) of the material was studied by modified Kurtz–Perry powder technique. The complex exhibits good antibacterial and antifungal activities against various bacteria and fungi species.

► The complex, 3,5-dimethylpyrrazolinium picrate was grown by slow evaporation method.
► The thermal stability of the complex indicates that it was stable up to 140 °C.
► The complex exhibited good antibacterial and antifungal activities.
► The nonlinear optical property of the complex was studied.