1 ,10-phenanthroline Absorption spectroscopy Carbolines Crystal atomic structure Density functional theory Electronic transition Ground state Ground state geometry Ligands Mass spectrometry Molecular Structure Rhenium Rhenium compounds Spectrometry Spectrometry technique Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization Spectrophotometry, Ultraviolet Spectroscopic characterization Spectroscopy, Fourier Transform Infrared Synthesis (chemical) Trifluoromethanesulfonate UV-VIS absorption spectra Ultraviolet spectroscopy X ray diffraction X ray structural analysis X-Ray Diffraction beta carboline carboline derivative chemical structure chemistry