27 documents found, page 1 of 3
New Insights on the Vibrational Dynamics of 2-Methoxy-, 4-Methoxy- and 4-Ethoxy...
Ribeiro-Claro, Paulo J. A.; Vaz, Pedro D.; Nolasco, Mariela M.; Gil, Francisco P. S. C.; Carvalho, Luís A. E. Batista deThe dynamics of 2-methoxybenzaldehyde, 4-methoxybenzaldehyde, and 4-ethoxybenzaldehyde in the solid state are assessed through INS spectroscopy combined with periodic DFT calculations. In the absence of experimental data for 4-ethoxybenzaldehyde, a tentative crystal structure, based on its similarity with 4-methoxybenzaldehyde, is considered and evaluated. The excellent agreement between calculated and experime...
Vibrational Dynamics of Crystalline 4-Phenylbenzaldehyde from INS Spectra and P...
Nolasco, Mariela M.; Araujo, Catarina F.; Vaz, Pedro D.; Amado, Ana M.; Ribeiro-Claro, Paulo J. A.The present work emphasizes the value of periodic density functional theory (DFT) calculations in the assessment of the vibrational spectra of molecular crystals. Periodic calculations provide a nearly one-to-one match between the calculated and observed bands in the inelastic neutron scattering (INS) spectrum of crystalline 4-phenylbenzaldehyde, thus validating their assignment and correcting previous reports ...
Vibrational dynamics of 4-fluorobenzaldehyde from periodic DFT calculations
Ribeiro-Claro, Paulo J.A.; Vaz, Pedro D.; Nolasco, Mariela M.; Araújo, Catarina F.; Gil, F.P.S.C.; Amado, Ana M.A thorough vibrational portrait of 4-fluorobenzaldehyde is presented, covering Infrared (Mid- and Far-), Raman and Inelastic Neutron Scattering (INS) spectra. Periodic DFT calculations (CASTEP) of a model 4FB crystal proved useful for vibrational assignment, yielding estimates of experimental spectra with near one-to-one correspondence – including the correct estimation of overtone and combination modes. A stri...
Understanding the vibrational spectra of crystalline isoniazid: Raman, IR and I...
Ribeiro-Claro, Paulo J. A.; Vaz, Pedro D.; Nolasco, Mariela M.; Amado, Ana M.This work presents a comprehensive spectroscopic analysis of crystalline isoniazid, one of the main drugs in tuberculosis chemotherapy, using a blend of spectroscopic and computational methods. Mid- and far-infrared, Raman, and inelastic neutron scattering spectroscopies, with contribution of isotopic substitution are combined with discrete and periodic DFT quantum chemical calculations. This combined approach ...
Vibrational and conformational studies of 1,3-diaminopropane and its N-deuterat...
Mendes, Sofia R. O.; Amado, Ana M.; Tomkinson, John; Marques, M. Paula M.; Carvalho, Luís A. E. Batista de
Conformational insights and vibrational study of a promising anticancer agent: ...
Fiuza, Sónia M.; Amado, Ana M.; Parker, Stewart F.; Marques, Maria Paula M.; Carvalho, Luís A. E. Batista de
On the Relevance of Considering the Intermolecular Interactions on the Predicti...
Amado, Ana M.; Fiúza, Sónia M.; Batista de Carvalho, Luís A. E.; Ribeiro-Claro, Paulo J. A.The effects of implicitly considering the effects of hydrogen bonding on the molecular properties, such as vibrational frequencies, were inferred on the basis of DFT calculations. Several clusters of isopropylamine were assembled and theoretically characterized. The results showed that maximum H-bond cooperativity is achieved when the amine group acts simultaneously as donor and acceptor. The effect of H-bond c...
On the Relevance of Considering the Intermolecular Interactions on the Predicti...
Amado, Ana M.; Fiuza, Sonia M.; Batista de Carvalho, Luis A. E.; Ribeiro-Claro, Paulo J. A.The effects of implicitly considering the effects of hydrogen bonding on the molecular properties, such as vibrational frequencies, were inferred on the basis of DFT calculations. Several clusters of isopropylamine were assembled and theoretically characterized. The results showed that maximum H-bond cooperativity is achieved when the amine group acts simultaneously as donor and acceptor. The effect of H-bond c...
VIBRATIONAL SPECTROSCOPY (FTIR-ATR AND FT-RAMAN) - A Rapid and Useful Tool for ...
Pereira, Leonel; Amado, Ana M.; Ribeiro-Claro, Paulo J. A.; van de Velde, FredThe wide industrial application of phycocolloids (e.g. alginates, agar and carrageenans) is based on their particular properties to form gels in aqueous solution. Recently, new spectroscopic techniques have provided more accurate identification of the natural composition of the polysaccharides produced by these seaweeds. With the combination of two spectroscopic techniques (FTIR-ATR and FT-Raman) it is possible...
Identification of selected seaweed polysaccharides (phycocolloids) by vibration...
Pereira, Leonel; Amado, Ana M.; Critchley, Alan T.; Velde, Fred van de; Ribeiro-Claro, Paulo J. A.The wide industrial application of phycocolloids (e.g. alginates, agar and carrageenans) is based on their particular properties to form gels in aqueous solution. These seaweed polysaccharides present a chemical structure related with the taxonomic position of the algae: carrageenans are produced by carrageenophytes (red algae belonging mainly to the genera Kappaphycus, Eucheuma, Chondrus, Gigartina and Chondra...