Matrix-isolation infrared spectroscopy of 2,3-, 2,4-, 2,5- and 3,4-difluorobenzaldehydes

Microwave spectral studies of 2,4-difluorobenzaldehyde: O-trans conformer

“…The ground state geometry of the molecule has been optimized by single point energy calculation and then the total energy was scanned by rotating about the 1CA12C bond (represented by the dihedral angle (d) 2C1CA12C14O in degree) in steps of 10°. The energy difference between the O-cis (d = 0°) and O-trans (d = 180°) rotamers was found to be 820.8 cm À1 which is in good agreement with the experimental value of 820 ± 3 cm À1 obtained by Itoh et al [7] using infrared data. The potential energy surface plot is shown in Fig.…”

“…Since the previous emission and infrared spectral data [6,7] conclusively proved the existence of the O-trans rotamer for 2,4-DFBD as the most stable conformer in the gas phase, quantum chemical calculations were performed for this rotamer using Gaussian-09 package [11]. Calculated values of the rotational constants were used to predict the spectrum in 18.0-37.0 GHz frequency range.…”

“…The 'pump' frequencies sharing the a-type Q-branch transitions 14 (7, 7)-14 (7,8), 15 (7, 8)-15 (7,9) and 16 (7,9)-16 (7, 10) at 2.4 MHz, 6.3 MHz and 15.6 MHz respectively were used during the RFMWDR scan. A schematic energy level diagram for one of the double resonance scans is shown in Fig.…”

“…Alonso et al [5] have also reported the assignment of a set of l a -and l b -type rotational transitions belonging to the ground and several excited torsional states for 4-fluorobenzaldehyde. Itoh et al [6,7] have demonstrated the existence of only the anti rotamer (O-trans) for 2, 3-, 2,4-and 2,5-difluorobenzaldehydes vapors through an analysis of emission and infrared spectral data. However, to the best of our knowledge, no microwave spec- tral studies for any difluoro substituted benzaldehyde have been reported so far.…”

Resonant two-photon mass-analyzed threshold ionization of 2,5-difluoroaniline

“…Spectroscopic studies of tri-substituted benzenes [1][2][3][4][5][6] are quite challenging because these molecules may have various isomers whose spectral ranges overlap closely to one another. Some isomers have similar physical but different chemical properties.…”