Showing papers on "Molecule published in 2002"
TL;DR: In this article, the crystal and molecular structure of cellulose Iβ were determined using synchrotron and neutron diffraction data recorded from oriented fibrous samples prepared by aligning cellulose microcrystals from tunicin.
Abstract: The crystal and molecular structure together with the hydrogen-bonding system in cellulose Iβ has been determined using synchrotron and neutron diffraction data recorded from oriented fibrous samples prepared by aligning cellulose microcrystals from tunicin. These samples diffracted both synchrotron X-rays and neutrons to better than 1 A resolution (>300 unique reflections; P21). The X-ray data were used to determine the C and O atom positions. The resulting structure consisted of two parallel chains having slightly different conformations and organized in sheets packed in a “parallel-up” fashion, with all hydroxymethyl groups adopting the tg conformation. The positions of hydrogen atoms involved in hydrogen-bonding were determined from a Fourier-difference analysis using neutron diffraction data collected from hydrogenated and deuterated samples. The hydrogen atoms involved in the intramolecular O3···O5 hydrogen bonds have well-defined positions, whereas those corresponding to O2 and O6 covered a wider v...
2,583 citations
TL;DR: Recent advances in chemical syntheses of biodegradable polymers from the standpoint of molecular design are reviewed, with emphasis on controlled synthesis, and their biodegradation is discussed in relation to the molecular structure.
1,073 citations
TL;DR: This work uses external photostimulation to switch the fluorescence on and off from a single photochromic molecule embedded in a polymer film due to photo-isomerization of the molecule, which may eventually find application in erasable optical data-storage elements.
Abstract: The signal from a gaudy ring molecule flashes on and off as light flicks it open and shut Fluorescent properties can be useful not only for tracking individual molecules within a microenvironment, but also in molecular-scale opto-electronics Here we use external photostimulation to switch the fluorescence on and off from a single photochromic molecule embedded in a polymer film This digital response is due to photo-isomerization of the molecule, which may eventually find application in erasable optical data-storage elements
1,036 citations
TL;DR: A linear free energy approach is used to characterize 17 RTILs on the basis of their distinct multiple solvation interactions with probe solute molecules and provides data that can be used to help identify the interactions and properties that are important for specific chemical applications.
Abstract: Room-temperature ionic liquids (RTILs) are useful in many chemical applications. Recent publications have attempted to determine the polarity of RTILs using empirical solvent polarity scales. The results have indicated that most RTILs have similar polarities. Nevertheless, RTILs are capable of behaving quite differently when used as solvents in organic synthesis, matrixes in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, liquid−liquid extraction, and as stationary phases in gas chromatography. The work presented in this study uses a linear free energy approach to characterize 17 RTILs on the basis of their distinct multiple solvation interactions with probe solute molecules. This model provides data that can be used to help identify the interactions and properties that are important for specific chemical applications.
1,028 citations
TL;DR: An efficient synthesis of 1D, 2D and 3D polyrotaxanes with high structural regularity and molecular necklaces has been achieved by a combination of self-assembly and coordination chemistry.
Abstract: Mechanically interlocked molecules incorporating cucurbituril (CB[6]) as a molecular ‘bead’ and their supramolecular assemblies are described. An efficient synthesis of 1D, 2D and 3D polyrotaxanes with high structural regularity and molecular necklaces has been achieved by a combination of self-assembly and coordination chemistry. The functional aspects of these interlocked molecules and their supramolecular assemblies, including molecular machines and switches based on [2]rotaxanes, a 2D polyrotaxane with large cavities and channels, pseudorotaxane-terminated dendrimers, and interaction of pseudorotaxanes containing polyamines and CB[6] with DNA are also described.
872 citations
TL;DR: The solution structures and transport mechanisms of hydrated hydroxide are reported from first-principles computer simulations that explicitly treat quantum and thermal fluctuations of all nuclei and find that the transport mechanism differs significantly from the proton hole picture.
Abstract: Compared to other ions, protons (H+) and hydroxide ions (OH-) exhibit anomalously high mobilities in aqueous solutions1. On a qualitative level, this behaviour has long been explained by ‘structural diffusion’—the continuous interconversion between hydration complexes driven by fluctuations in the solvation shell of the hydrated ions. Detailed investigations have led to a clear understanding of the proton transport mechanism at the molecular level2,3,4,5,6,7,8. In contrast, hydroxide ion mobility in basic solutions has received far less attention2,3,9,10, even though bases and base catalysis play important roles in many organic and biochemical reactions and in the chemical industry. The reason for this may be attributed to the century-old notion11 that a hydrated OH- can be regarded as a water molecule missing a proton, and that the transport mechanism of such a ‘proton hole’ can be inferred from that of an excess proton by simply reversing hydrogen bond polarities11,12,13,14,15,16,17,18. However, recent studies2,3 have identified OH- hydration complexes that bear little structural similarity to proton hydration complexes. Here we report the solution structures and transport mechanisms of hydrated hydroxide, which we obtained from first-principles computer simulations that explicitly treat quantum and thermal fluctuations of all nuclei19,20,21. We find that the transport mechanism, which differs significantly from the proton hole picture, involves an interplay between the previously identified hydration complexes2,3 and is strongly influenced by nuclear quantum effects.
835 citations
TL;DR: It is shown that a single hydrogen molecule can form a stable bridge between platinum electrodes, and represents a simple test system in which to understand fundamental transport properties of single-molecule devices.
Abstract: Recent years have shown steady progress towards molecular electronics, in which molecules form basic components such as switches, diodes and electronic mixers. Often, a scanning tunnelling microscope is used to address an individual molecule, although this arrangement does not provide long-term stability. Therefore, metal-molecule-metal links using break-junction devices have also been explored; however, it is difficult to establish unambiguously that a single molecule forms the contact. Here we show that a single hydrogen molecule can form a stable bridge between platinum electrodes. In contrast to results for organic molecules, the bridge has a nearly perfect conductance of one quantum unit, carried by a single channel. The hydrogen bridge represents a simple test system in which to understand fundamental transport properties of single-molecule devices.
820 citations
TL;DR: In this article, a review of the data characterizing CO adsorption on surface cationic sites of oxides including supported materials and microporous and mesoporous materials is presented.
Abstract: The review is a summary and analysis of the data characterizing CO adsorption on surface cationic sites of oxides including supported materials and microporous and mesoporous materials. The contributions of various types of CO bonding to the IR frequency shifts of carbon-bonded molecules are analyzed, namely, the increase of the CO stretching frequency in cases of electrostatic and σ bonding and the decrease of the frequency with π bonding. Polycarbonyls, bridging CO, oxygen-bonded CO, and tilted CO are also considered. The main part of the review is a collection of the experimental results characterizing carbonyls of individual metal ions. The spectral behavior of CO bonded to metal atoms is also assessed in the cases when the metal ions are easily reduced to metal (Cu, Ag, Au, Pd, or Pt) or cationic carbonyls are produced after CO adsorption on supported metals (Ru, Rh, Ir, and Os). The interaction of CO with surface OH groups is also considered. It is demonstrated that IR spectroscopy of adsorbed CO is an efficient methodology to characterize cationic surface sites in terms of their nature, oxidation states, coordination environment and coordinative unsaturation, and location at faces, edges or corners of microcrystallites. When applied to materials with surface hydroxyl groups CO undergoes hydrogen bonding and information can be collected on the proton acid strength.
562 citations
TL;DR: The use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA).
Abstract: The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules.
556 citations
TL;DR: The direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements is reported.
Abstract: We report the direct observation of dioxygen molecules physisorbed in the nanochannels of a microporous copper coordination polymer by the MEM (maximum entropy method)/Rietveld method, using in situ high-resolution synchrotron x-ray powder diffraction measurements. The obtained MEM electron density revealed that van der Waals dimers of physisorbed O2 locate in the middle of nanochannels and form a one-dimensional ladder structure aligned to the host channel structure. The observed O–O stretching Raman band and magnetic susceptibilities are characteristic of the confined O2 molecules in one-dimensional nanochannels of CPL-1 (coordination polymer 1 with pillared layer structure).
547 citations
TL;DR: Scanning tunnelling microscopy studies of cysteine adsorbed to a (110) gold surface show that molecular pairs formed from a racemic mixture of this naturally occurring amino acid are exclusively homochiral, and that their binding to the gold surface is associated with local surface restructuring.
Abstract: Stereochemistry plays a central role in controlling molecular recognition and interaction: the chemical and biological properties of molecules depend not only on the nature of their constituent atoms but also on how these atoms are positioned in space. Chiral specificity is consequently fundamental in chemical biology and pharmacology1,2 and has accordingly been widely studied. Advances in scanning probe microscopies now make it possible to probe chiral phenomena at surfaces at the molecular level. These methods have been used to determine the chirality of adsorbed molecules3,4,5, and to provide direct evidence for chiral discrimination in molecular interactions6 and the spontaneous resolution of adsorbates into extended enantiomerically pure overlayers3,7,8,9. Here we report scanning tunnelling microscopy studies of cysteine adsorbed to a (110) gold surface, which show that molecular pairs formed from a racemic mixture of this naturally occurring amino acid are exclusively homochiral, and that their binding to the gold surface is associated with local surface restructuring. Density-functional theory10 calculations indicate that the chiral specificity of the dimer formation process is driven by the optimization of three bonds on each cysteine molecule. These findings thus provide a clear molecular-level illustration of the well known three-point contact model11,12 for chiral recognition in a simple bimolecular system.
TL;DR: It is shown that in the first layer all the molecules bind directly to the surface and to each other through the in-layer H bonds without dissociation, creating a nearly flat overlayer.
Abstract: We address the adsorption of water on Pt(111) using x-ray absorption, x-ray emission, and x-ray photoelectron spectroscopy along with calculations in the framework of density functional theory. Using the direct relationship between the electronic structure and adsorbate geometry, we show that in the first layer all the molecules bind directly to the surface and to each other through the in-layer H bonds without dissociation, creating a nearly flat overlayer. The water molecules are adsorbed through alternating metal-oxygen (M-O) and metal-hydrogen (M-HO) bonds.
TL;DR: It is shown that the optical properties of ZnS-capped CdSe quantum dots are sensitive to environmental factors such as pH and divalent cations, leading to the potential use of quantum dots in molecular sensing.
Abstract: Semiconductor nanoparticles in the size range of 2-6 nm are of great current interest, not only because of their size-tunable properties but also because of their dimensional similarity with bio- logical macromolecules (e.g., nucleic acids and proteins). This simi- larity could allow an integration of nanomaterials with biological mol- ecules, which would have applications in medical diagnostics, targeted therapeutics, and high-throughput drug screening. Here we report new developments in preparing highly luminescent and bio- compatible CdSe quantum dots (QDs), and in synthesizing QD- encoded micro- and nano-beads in the size range of 100 nm-10 mm. We show that the optical properties of ZnS-capped CdSe quantum dots are sensitive to environmental factors such as pH and divalent cations, leading to the potential use of quantum dots in molecular sensing. We also show that chemically modified proteins can be used to coat the surface of water-soluble QDs, to restore their fluorescence, and to provide functional groups for bioconjugation. For multiplexed optical encoding, we have prepared large microbeads with sizes simi- lar to that of mammalian cells, and small nanobeads with sizes similar
TL;DR: The QM calculations of the torsional energy surface for rotation about vinyl-methylene bonds reveal low barriers to rotation, indicating an intrinsic propensity toward flexibility and an unusually high degree of conformational flexibility of polyunsaturated hydrocarbon chains in membranes.
Abstract: Polyunsaturated lipids are an essential component of biological membranes, influencing order and dynamics of lipids, protein-lipid interaction, and membrane transport properties. To gain an atomic level picture of the impact of polyunsaturation on membrane properties, quantum mechanical (QM) and empirical force field based calculations have been undertaken. The QM calculations of the torsional energy surface for rotation about vinyl-methylene bonds reveal low barriers to rotation, indicating an intrinsic propensity toward flexibility. Based on QM and experimental data, empirical force field parameters were developed for polyunsaturated lipids and applied in a 16 ns molecular dynamics (MD) simulation of a 1-stearoyl-2-docosahexaenoyl-sn-glyerco-3-phosphocholine (SDPC) lipid bilayer. The simulation results are in good agreement with experimental data, suggesting an unusually high degree of conformational flexibility of polyunsaturated hydrocarbon chains in membranes. The detailed analysis of chain conformation and dynamics by simulations is aiding the interpretation of experimental data and is useful for understanding the unique role of polyunsaturated lipids in biological membranes. The complete force field is included as Supporting Information and is available from http://www.pharmacy.umaryland.edu/faculty/amackere/research.html.
TL;DR: Calculations from first principles show that the wetting layer observed on Ru(0001) cannot be formed of undissociated water molecules, and an energetically favorable alternative is a half-dissociated monolayer wherein water molecules and hydroxyl fragments are hydrogen-bonded in a hexagonal structure and hydrogen atoms bind directly to the metal.
Abstract: Initial water deposition on the moderately reactive precious metal surface Ru(0001) has been thought to produce an ice-like bilayer. However, calculations from first principles show that the wetting layer observed on Ru(0001) cannot be formed of undissociated water molecules. An energetically favorable alternative, consistent with the remarkable observation that the wetting layer's oxygen atoms are nearly coplanar, is a half-dissociated monolayer wherein water molecules and hydroxyl fragments are hydrogen-bonded in a hexagonal structure and hydrogen atoms bind directly to the metal.
TL;DR: A method for optically encoding micrometre-sized nanostructured particles of porous silicon using a periodic electrochemical etch and a simple antibody-based bioassay using fluorescently tagged proteins demonstrates the encoding strategy in biologically relevant media.
Abstract: Strategies to encode or label small particles or beads for use in high-throughput screening and bioassay applications focus on either spatially differentiated, on-chip arrays or random distributions of encoded beads. Attempts to encode large numbers of polymeric, metallic or glass beads in random arrays or in fluid suspension have used a variety of entities to provide coded elements (bits)--fluorescent molecules, molecules with specific vibrational signatures, quantum dots, or discrete metallic layers. Here we report a method for optically encoding micrometre-sized nanostructured particles of porous silicon. We generate multilayered porous films in crystalline silicon using a periodic electrochemical etch. This results in photonic crystals with well-resolved and narrow optical reflectivity features, whose wavelengths are determined by the etching parameters. Millions of possible codes can be prepared this way. Micrometre-sized particles are then produced by ultrasonic fracture, mechanical grinding or by lithographic means. A simple antibody-based bioassay using fluorescently tagged proteins demonstrates the encoding strategy in biologically relevant media.
TL;DR: This paper demonstrates dielectrophoretic trapping using insulating constrictions at far lower frequencies than are feasible with metallic trapping structures because of water electrolysis, and demonstrates that electrodelessdielectrophoresis (EDEP) can be used for concentration and patterning of both single-strand and double-stranded DNA.
TL;DR: The results suggest that ionic strength effects may largely arise from local effects related to the hydrated volume of the ion--that is, from space filling, osmotic, water activity, surface tension and hydration shell overlap effects rather than from long-range electric field effects.
TL;DR: A large molecule in which four perylene-3,4:9,10-tetracarboxydiimide (PDI) molecules that both collect photons and accept electrons are attached to a central zinc 5,10,15,20-Tetraphenylporphyrin (ZnTPP) electron donor self-assembles into ordered nanoparticles both in solution and in the solid-state, driven by van der Waals stacking of the PDI molecules.
Abstract: Molecules designed to carry out photochemical energy conversion typically employ several sequential electron transfers, as do photosynthetic proteins. Yet, these molecules typically do not achieve the extensive charge transport characteristic of semiconductor devices. We have prepared a large molecule in which four perylene-3,4:9,10-tetracarboxydiimide (PDI) molecules that both collect photons and accept electrons are attached to a central zinc 5,10,15,20-tetraphenylporphyrin (ZnTPP) electron donor. This molecule self-assembles into ordered nanoparticles both in solution and in the solid-state, driven by van der Waals stacking of the PDI molecules. Photoexcitation of the nanoparticles results in quantitative charge separation in 3.2 ps to form ZnTPP+PDI- radical ion pairs, in which the radical anion rapidly migrates to PDI molecules that are, on average, 21 A away, as evidenced by magnetic field effects on the yield of the PDI triplet state that results from radical ion pair recombination. These nanoparti...
TL;DR: The understanding of biocatalysis has been enhanced significantly through the isolation and comprehensive characterization of the Cu(2)(mu-O)(2) and Fe(2](mu- O)(2), which has led to the development of new mechanistic notions about how non-heme multimetal enzymes may function in the activation of dioxygen to catalyze a diverse array of organic transformations.
Abstract: Although quite a familiar feature in high-valent manganese chemistry, the M(2)(mu-O)(2) diamond core motif has only recently been found in synthetic complexes for M=Cu or Fe. Structural and spectroscopic characterization of these more reactive Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) compounds has been possible through use of appropriately designed supporting ligands, low-temperature handling methods, and techniques such as electrospray ionization mass spectrometry and X-ray crystallography with area detector instrumentation for rapid data collection. Despite differences in electronic structures that have been revealed through experimental and theoretical studies, Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) cores exhibit analogously covalent metal-oxo bonding, remarkably congruent Raman and extended X-ray absorption fine structure (EXAFS) signatures, and similar tendencies to abstract hydrogen atoms from substrates. Core isomerization is another common reaction attribute, although different pathways are traversed; for Fe, bridge-to-terminal oxo migration has been discovered, while for Cu, reversible formation of an O-O bond to yield a peroxo isomer has been identified. Our understanding of biocatalysis has been enhanced significantly through the isolation and comprehensive characterization of the Cu(2)(mu-O)(2) and Fe(2)(mu-O)(2) complexes. In particular, it has led to the development of new mechanistic notions about how non-heme multimetal enzymes, such as methane monooxygenases, fatty acid desaturase, and tyrosinase, may function in the activation of dioxygen to catalyze a diverse array of organic transformations.
TL;DR: In this paper, the permeability properties of hollow polyelectrolyte multilayer capsules for different substances were investigated as a function of pH and salt concentration, and it was shown that the capsules are closed at a pH value of 8 and higher, but at pH lower than 6 the macromolecules permeate into the capsule interior.
TL;DR: The lifetime of the hydrogen bond between a PHG and a water molecule is found to be much longer than that between any two water molecules, and is likely to be a general feature of hydrophilic surfaces of organized assemblies.
Abstract: The dynamics of hydrogen bonds among water molecules themselves and with the polar head groups (PHG) at a micellar surface have been investigated by long molecular dynamics simulations. The lifetime of the hydrogen bond between a PHG and a water molecule is found to be much longer than that between any two water molecules, and is likely to be a general feature of hydrophilic surfaces of organized assemblies. Analyses of individual water trajectories suggest that water molecules can remain bound to the micellar surface for more than 100 ps. The activation energy for such a transition from the bound to a free state for the water molecules is estimated to be about 3.5 kcal/mol.
TL;DR: The synthesis and characterization of the so far largest polycyclic aromatic hydrocarbon, containing 222 carbon atoms or 37 separate benzene units is presented, based on isotopically resolved MALDI-TOF mass spectra.
Abstract: In this paper we present the synthesis and characterization of the so far largest polycyclic aromatic hydrocarbon (PAH), containing 222 carbon atoms or 37 separate benzene units. First a suitable three-dimensional oligophenylene precursor molecule is built up by a sequence of Diels-Alder and cyclotrimerization reactions and then planarized in the final step by oxidative cyclodehydrogenation to the corresponding hexagonal PAH. Structural proof is based on isotopically resolved MALDI-TOF mass spectra and electronic characteristics are studied by UV/Vis spectroscopy.
TL;DR: Mossbauer spectroscopy in situ was used to study the effect of high-temperature activation on the evolution of iron introduced into a ZSM-5 zeolite matrix by various methods as discussed by the authors.
TL;DR: The large observed binding constants are ascribed to the presence of a phenanthroline-coordinated cationic charge that decreases the electron density on the pyrrole NH protons and pure electrostatic effects.
Abstract: Novel anion recognition host molecules, tris-1,10-phenanthroline cobalt(III) and bis-2,2'-bipyridine mono-1,10-phenanthroline ruthenium(II) complexes bearing fused dipyrrolylquinoxaline moieties have been synthesized. As determined by UV-vis spectroscopic and electrochemical studies, these metal complexes bind fluoride with high affinity in polar media both in absolute terms and relative to the metal-free phenanthroline dipyrrolylquinozaline precursor from which they are derived (fluoride is bound to the tris-1,10-phenanthroline cobalt(III) dipyrrolylquinoxaline system with a 1:1 binding constant of 54 000 M-1 in DMSO). The large observed binding constants are ascribed to two factors, (i) the presence of a phenanthroline-coordinated cationic charge that decreases the electron density on the pyrrole NH protons and (ii) pure electrostatic effects.
TL;DR: In this article, the Norskov-Newns-Lundqvist model was used to detect chemically induced e−h pairs with thin metal film Si Schottky diodes.
TL;DR: The chemomechanical coupling of the hydrolysis of ATP to the mechanical work of kinesin is studied by analysing the individual stepwise movements according to the directionality of the movements.
Abstract: The molecular motor kinesin travels processively along a microtubule in a stepwise manner. Here we have studied the chemomechanical coupling of the hydrolysis of ATP to the mechanical work of kinesin by analysing the individual stepwise movements according to the directionality of the movements. Kinesin molecules move primarily in the forward direction and only occasionally in the backward direction. The hydrolysis of a single ATP molecule is coupled to either the forward or the backward movement. This bidirectional movement is well described by a model of Brownian motion assuming an asymmetric potential of activation energy. Thus, the stepwise movement along the microtubule is most probably due to Brownian motion that is biased towards the forward direction by chemical energy stored in ATP molecules.
TL;DR: In this article, the authors have determined structures, ionization potentials, and vertical detachment energies for neutral and charged bimetallic AgmAun[3⩽(m+n)5] clusters.
Abstract: Bimetallic silver–gold clusters offer an excellent opportunity to study changes in metallic versus “ionic” properties involving charge transfer as a function of the size and the composition, particularly when compared to pure silver and gold clusters. We have determined structures, ionization potentials, and vertical detachment energies for neutral and charged bimetallic AgmAun [3⩽(m+n)⩽5] clusters. Calculated VDE values compare well with available experimental data. In the stable structures of these clusters Au atoms assume positions which favor the charge transfer from Ag atoms. Heteronuclear bonding is usually preferred to homonuclear bonding in clusters with equal numbers of hetero atoms. In fact, stable structures of neutral Ag2Au2, Ag3Au3, and Ag4Au4 clusters are characterized by the maximum number of hetero bonds and peripheral positions of Au atoms. Bimetallic tetramer as well as hexamer are planar and have common structural properties with corresponding one-component systems, while Ag4Au4 and Ag8...
TL;DR: This work investigates the role of a weaker, but cooperative, C-H...O hydrogen bond as an additional stabilizing interaction in the solvation of polycarbonyl moieties with hydrogen atoms attached directly to the carbonyl carbon or to the alpha-carbon atom.
Abstract: Understanding the fundamental principles for the design of CO2-philic materials is of growing importance due to the potential for enabling “green” chemistry and technologies in liquid and supercritical CO2 as alternative solvent systems. Recently, there have been numerous efforts to develop hydrocarbon-based CO2-philes containing carbonyl groups, which are known to interact through a Lewis acid−Lewis base (LA−LB) interaction with CO2 molecules, thereby providing the necessary solvation energy for dissolution. In this work, we investigate the role of a weaker, but cooperative, C−H···O hydrogen bond as an additional stabilizing interaction in the solvation of polycarbonyl moieties with hydrogen atoms attached directly to the carbonyl carbon or to the α-carbon atom. Ab initio calculations are performed on simple intermolecular complexes of CO2 with compounds capable of acting as Lewis bases. Systems studied in different interaction configurations include formaldehyde, acetaldehyde, acetic acid, and methyl ac...