2-cyclopenten-1-ol DFT DSC/TGA analysis FTIR FTIR spectroscopy GIAO Hirshfeld surface analysis IR and Raman spectroscopy Matrix isolation NMR NaYF4:Er,Yb PLS-DA QTAiM analysis X-ray crystallography ab initio attention deficit and hyperactivity disorder (ADHD) carbanion monosubstituted 4-tolyl-1,2,4-triazol-1-ium phenacylids carbonyls chemometrics ciprofloxacin–biguanide bismuth complex complexes computational chemistry conformational landscape conformations crystal features crystal structure cyanide dihydrofolate reductase dimers dissociation