The Research Group on Low Temperature Molecular Spectroscopy integrates the Centre of Chemistry of Coimbra. It integrated the Photochemistry and Molecular Spectroscopy Group until very recently. The group integrates 3 senior scientists (Ph.D. holders) and several young researchers. During the last 4 years, the group published ca. 60 papers in international journals with high impact factor, 2 specialised books and presented more than 70 communications in international conferences.
The main research areas in which the group has been involved are outlined below.



The general problem under study is structural and vibrational characterization of low temperature matrix-isolated molecules by vibrational spectroscopy. Thermal conformational interconversion processes in both the gaseous phase and occurring during matrix deposition or within the deposited matrices are also addressed in this research program. In addition, photochemical processes, in particular vibrational energy redistribution/relaxation in simple molecules isolated in matrices at low temperature were also studied. The potential energy surfaces of a considerable number of different molecules with biological or industrial interest have been studied regarding their spectroscopically observable minima. The experimentally accessible conformers predicted on the basis of sophisticated theoretical ab initio and/or DFT methods were afterwards searched by matrix-isolation and low temperature solid state FTIR spectroscopy, their structure characterized and their reactivity (either thermal or photochemical) studied. Exceptional phenomena such as conformational cooling during matrix deposition [“Missing Conformers: Comparative Study of Conformational Cooling in Cyanoacetic Acid and Methyl Cyanoacetate Isolated in Low Temperature Inert Gas Matrixes.”, I.D.Reva, S.G.Stepanian, L.Adamowicz and R.Fausto, Chem.Phys. Lett., 364 (2003) 361], inversion of the lowest energy conformational states upon phase change (including trapping of the molecule under study in a noble gas matrix) [“Low Temperature FT-IR and Molecular Orbital Study of N,N-Dimethyl Glycine Methyl Ester: Proof for Different Ground Conformational States in Gas Phase and in Condensed Media”, A.Gómez-Zavaglia and R. Fausto, PCCP, 5 (2003) 52.], conformationally selective aggregation [“Matrix-Isolation FT-IR Spectra and Molecular Orbital Calculations on Neutral N,N-Dimethylglycine”, A.Gómez-Zavaglia, I.D.Reva and R. Fausto, PCCP, 5 (2003) 41.], observation of conformer dependent photodegradation pathways upon UV excitation of matrix isolated molecules [“Infrared-Induced Conformational Interconversion in Carboxylic Acids Isolated in Low-Temperature Rare-Gas Matrices”, E.M.S. Maçôas, L. Kriachtchev, M. Pettersson, J. Lundell, R. Fausto and M. Räsänen, Vibrat.Spectrosc., 34 (2004) 73.], in situ photoproduction of Dewar-like bicyclolactones, ketenes and isocyanides in low temperature matrices [“Matrix-Isolation FTIR and Theoretical Study of the UV-Induced Photochemistry of a-Pyrone”, S. Breda, I. Reva, L. Lapinski and R. Fausto, PCCP, 6 (2004) (in press)], first observation of neutral forms of aminoacids in the pure solid state [“Low Temperature Solid-State FTIR Study of Glycine, Sarcosine and N,N-Dimethylglycine: Observation of Neutral Forms of Simple a-Aminoacids in the Solid State”, A. Gómez-Zavaglia and R. Fausto, PCCP, 5 (2003) 3154], production of reactive photoexcitation vibrational spectra of matrix isolated molecules [“Reactive Vibrational Excitation Spectroscopy of Trans-Formic Acid in Solid Argon: Solid State Effects on the Vibrational Spectroscopy and Quantum Yield Determination for the Induced Isomerization”, E.M.S. Maçôas, L. Kriachtchev, M. Pettersson, R. Fausto and M. Räsänen, J.Chem.Phys., J.Chem.Phys., 119 (2003) 1.], for example, have been described in the numerous articles published by the group during the last few years, from which the papers here mentioned constitute notable and recent examples.


This is a new branch of research of the Photochemistry and Molecular Spectroscopy Research Group. Long term cryogenic storage of biological material, like living cells and tissues, has an enormous importance in several areas of the human activity (e.g., transplantation). In general, the methods developed for the cryopreservation of cells have not proved to be directly transferable to multicellular, organised tissues and organs. For these systems, vitrification (glass formation) has been recognised as the most promising approach to overcome the problem of ice formation during freezing, which in the case of the highly organised structures of an organ or tissue has been shown to result in devastating and fatal damage. Vitrification requires that the biomaterial be perfused with a suitable cryoprotectant, the role of which is to protect the material from the physicochemical and biochemical effects of low temperatures, and also to promote the attainment of the vitreous state. The choice of a suitable cryoprotectant is critical to successful vitrification and depends on a number of factors, including solute toxicity, solute/water interactions and cooling rate. Unfortunately, with the cryoprotectants presently used, the concentration needs to be high to achieve complete vitrification and thus toxicity becomes a problem. This research program aims to develop new more efficient vitrifying procedures involving new cryoprotectants which present lower toxicity than those actually available. To attain this fundamental objective, a precise physicochemical characterisation of a series of substances and mixtures of substances, both at the molecular and thermodynamic levels, need to be first established. Three main families of closely related hydroxyl containing compounds and mixtures of these compounds are being investigated: (a) aminoalcohols [“Phase Transitions of 3-Amino-1-Propanol at Low Temperatures”, C.Cacela, A.Baudot, M.L.Duarte, R.Fausto, A.M.Matos-Beja, M.Ramos Silva and J.A.Paixão, J.Mol.Struct, 649 (2003) 143], (b) N-methyl substituted aminoacids [“Matrix-Isolation FT-IR Spectra and Molecular Orbital Calculations on Neutral N,N-Dimethylglycine”, A.Gómez-Zavaglia, I.D.Reva and R. Fausto, PCCP, 5 (2003) 41] and (c) “
a-hydroxy-substituted carbonyl compounds [“Structure and Vibrational Spectra of a-Hydroxy Isobutyric Acid in the Crystalline and Glassy Phases and Isolated in Inert Gas Matrixes”, S.Jarmelo and R.Fausto, PCCP, 4 (2002) 1555]. The families of molecules under study were selected on the basis of the accumulated experience and, in particular, because there are some evidence that the simultaneous presence in the solute molecule of proton attractor and donor moieties tends to increase its ability to promote vitrification at smaller concentrations. Recent biological tests on the first family of molecules shown that these compounds have excellent physicochemical properties to the desired application [“Thermal Study of Simple Amino-Alcohols as Cryoprotectants”, A.Baudot, C.Cacela, R.Fausto and M.L.Duarte, Cryobiology, 44 (2002) 150].



Rui Fausto is head of the group. He is associate professor and vice-president of the Directive Board of the Faculty of Sciences and Technology of the University of Coimbra. He graduated in Chemistry in 1984 and obtained his Ph.D. in Physical Chemistry (Molecular Structure) in 1988. His main research topics involve the study of physicochemical properties of molecular systems at low temperature by spectroscopy, thermodynamics and theoretical methods, the study of the redistribution energy processes in matrix-isolated molecules subjected either to electronic or vibrational photoexcitation and physicochemical characterization of cryoprotectant solutions.
Igor Reva is a post-doctoral fellow. He graduated in Molecular Biophysics in 1982 (Kharkov State University, Ukraine). Since then he has been carrying out research using cryogenic methods and involved into development of the low-temperature experimental equipment. In 1995 he obtained his PhD degree in Molecular Physics (Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine). He joined Coimbra group in 1999. His current research interests are related with studies of molecular structure and vibrational properties of molecular systems exhibiting conformational isomerism using experimental techniques (low temperature matrix isolation and infrared spectroscopy) and theoretical calculations.
Andrea Gómez-Zavaglia is a post-doctoral fellow. He graduated in Biochemistry in 1993 (University of Buenos Aires, Argentina) and obtained her PhD degree in Biological Sciences in 2000 (Institute for Low Temperature Food Preservation) working on preservation of lactic acid bacteria. Her main interests are connected with the development of efficient vitrifying procedures and new cryoprotectants. To attain this fundamental objective, a precise physicochemical characterisation of a series of substances and mixtures of substances, both at the molecular and thermodynamic levels, are being undertaken by complementary use of low temperature spectroscopic and calorimetric methods, together with cryobiology methods. Specific applications to biological material are also being considered, in particular the study of the role of cryoprotectants in the dehydration of biological membranes and their interaction with potential stress protectants.
Ermelinda Maçôas is a Ph.D. Student. Her interests are connected with the general problem of vibrational energy redistribution/relaxation in simple molecules isolated in matrices at low temperature. Her studies focus on the processes following vibrational excitation carried out either in the mid infrared (fundamental vibrations) or near infrared (overtones and combination tones). A systematic procedure of selective irradiation (in both the mid and near infrared regions) of a particular molecular species (conformer) and vibrational mode have been developed, which is followed by spectroscopic probing of the intramolecular energy redistribution/relaxation processes.
Susana Jarmelo is a Ph.D. Student. Her interests are centrered in the study of intermolecular interactions, in particular H-bonding, in enzyme-substrate systems. A novel experimental approach to determine the strength of H-bonds between serine and H-bond donors or acceptors are being developed. The governing premise is that the C-H bond strength of the alcohol carbon of serine, and consequently the C-H bond length and vibrational stretching frequency, are significantly perturbed by H-bond formation in a predictable and quantifiable manner. To look at these effects, extensive isotopical labelling of the substrates is being used to create a spectral window where both solvent and protein contributions are minimal.
Susana Breda is a Ph.D. Student. Her main research interests are centrered in the study of the vibrational spectra and photochemistry of heterocyclic compounds. A series of
a-pyrones and analogous compounds have already been studied in order to analyze the main photochemical reaction pathways in these compounds. The preferences for the different main reaction pathways were found to be dependent on the substitution at the heterocyclic ring, thus opening good perspectives for selective control of the photochemical processes by chemical modification of the heterocycles. This control might have applications in organic synthesis, as in the Diels Alder reactions.
Susy Lopes is studying for the Masters degree. Her research interests are related with the study of conformationally flexible molecules. Up to now, she has been studying dicarboxylic esters and other dicarbonyl compounds with important biological and industrial applications. The more specific problem of the influence of large amplitude – low frequency vibrations on molecular properties has been addressed successfully, both in the cases of single and double internal rotors.
Ana Borba
is studying for the Masters degree. Her research interests are the study of intermolecular interactions in matrix isolated chiral compounds with biological relevance, and sulphur containing molecules. The effects of chirality on the aggregation processes are particularly relevant in the field of molecular recognition and enzymatic catalysis.



Department of Chemistry
University of Coimbra
P-3004-535 Coimbra

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