Density Functional Theory Geometry Research Articles

Ab initio and DFT studies of the structure and vibrational spectra of anhydrous caffeine

Vibrational spectra and molecular structure of anhydrous caffeine have been systematically investigated by second order Moller–Plesset (MP2) perturbation theory and density functional theory (DFT) calculations. Vibrational assignments have been made and many previous ambiguous assignments in IR and Raman spectra are amended. The calculated DFT frequencies and intensities at B3LYP/6-311++G(2d,2p) level, were found to be in better agreement with the experimental values. It was found that DFT with B3LYP functional predicts harmonic vibrational wave numbers more close to experimentally observed value when it was performed on MP2 optimized geometry rather than DFT geometry. The calculated TD-DFT vertical excitation electronic energies of the valence excited states of anhydrous caffeine are found to be in consonance to the experimental absorption peaks.

An investigation of solute–solvent interactions in binary liquid mixtures of 3′-methoxyacetophenone: Using Raman spectroscopy and DFT calculations

Raman spectral measurements have been carried out for neat 3′-methoxy acetophenone (3′-MAP) and binary liquid mixtures of 3′-MAP in three solvents of different polarity. Also Density Functional Theory (DFT) geometry optimization and vibrational wavenumber calculation have been performed on monomer and dimer structures of 3′-MAP to analyze the experimentally observed Raman spectrum. Mulliken charge analysis has also been made on optimized geometries of 3′-MAP with solvents. The changes associated with the observed peak position, intensity and linewidth in the carbonyl stretching mode of 3′-MAP are explained as a consequence of intermolecular interactions between solute–solute and solute–solvent molecules. This analysis reports that the solute–solvent interaction is dominant in the case of binary liquid mixtures of 3′-MAP with ethanol compared to DMF and benzene.

Far-infrared absorption spectra of synthetically-prepared, ligated metal clusters with Au6, Au8, Au9 and Au6Pd metal cores

The far infra-red absorption spectra of a series of chemically synthesised, atomically precise phosphine-stabilised gold cluster compounds have been recorded using synchrotron light for the first time. Far-IR spectra of the Au6(Ph2P(CH2)3PPh2)4(NO3)2, Au8(PPh3)8(NO3)2, Au9(PPh3)8(NO3)3, and Pd(PPh3)Au6(PPh3)6(NO3)2 clusters reveal a complex series of peaks between 80 and 475 cm−1, for which all significant peaks can be unambiguously assigned by comparison with Density Functional Theory (DFT) geometry optimisations and frequency calculation. Strong absorptions in all spectra near 420 cm−1 are assigned to the P–Ph3 stretching vibrations. Distinct peaks within the spectrum of each specific cluster are assigned to the cluster core vibrations: 80.4 and 84.1 cm−1 (Au6) 165.1 and 166.4 cm−1 (Au8), 170.1 and 185.2 cm−1 (Au9), and 158.9, 195.2, and 206.7 cm−1 (Au6Pd). The positions of these peaks are similar to those observed to occur for the neutral Au7 cluster in the gas phase (Science, 2008, 321, 674–676). Au–P stretching vibrations only occur for Au6 near 420 cm−1, although they appear near 180 cm−1 for Au6Pd and involve gold core vibrations.

Synthesis and structural characterization of bis and tris(2-mercapto-1-methylbenzimidazolyl)hydroborato complexes: benzannulation promotes κ3-coordination

The benzannulated bis and tris(mercaptoimidazolyl)borohydride compounds, [BmMeBenz]Na and [TmMeBenz]Na, have been synthesized via the reactions of NaBH4 with two and three equivalents of 1-methyl-1,3-dihydro-2H-benzimidazole-2-thione, respectively. X-ray diffraction studies on the THF adducts, {μ-[BmMeBenz]Na(THF)₂}₂ and {[TmMeBenz]Na}₂(μ-THF)₃, indicate that both compounds are dinuclear but differ according to the nature of the bridging ligand. Specifically, {μ-[BmMeBenz]Na(THF)₂}₂ possesses bridging [BmMeBenz] ligands and terminal THF ligands, while {[TmMeBenz]Na}₂(μ-THF)₃ possesses terminal [TmMeBenz] ligands and bridging THF ligands. The tris(mercaptoimidazolyl)borohydride ligand of {[TmMeBenz]Na}₂(μ-THF)₃ coordinates in a κ³-manner, which is in marked contrast to the κ²-, κ¹- and κ⁰-modes that have been reported for various [TmMe]Na derivatives. Density functional theory (DFT) geometry optimization calculations of the anions [TmMeBenz]⁻ and [TmMe]⁻ in the gas phase indicate that the conformation required for κ³-S₃ coordination, i.e. one in which the three sulfur donors point away from the B-H group, is relatively more stable for [TmMeBenz]⁻ than for [TmMe]⁻, and thus provides a rationalization for the observation that benzannulation enables κ³-coordination of tris(mercaptoimidazolyl)borohydride ligand in {[TmMeBenz]Na}₂(μ-THF)₃. Furthermore, comparison of the molecular structure and IR spectroscopic properties of [TmMeBenz]Re(CO)₃ with those of [TmMe]Re(CO)₃ indicates that benzannulation reduces the electron donating properties of the ligand, but has little effect on its steric properties. {μ-[BmMeBenz]Na(THF)₂}₂ and {[TmMeBenz]Na}₂(μ-THF)₃ react with [Me₃PCuCl]₄ to give [BmMeBenz]CuPMe₃ and [TmMeBenz]CuPMe₃, the first pair of structurally related bis and tris(mercaptoimidazolyl)hydroborato copper(I) compounds.

Spectroscopic and Computational Studies of a Small-Molecule Functional Mimic of Iron Superoxide Dismutase, Iron 2,6-Diacetylpyridinebis(semioxamazide)

Iron 2,6-diacetylpyridinebis(semioxamazide) (Fe(dapsox)) is a heptacoordinate pentagonal bipyramidal, functional mimic of iron-dependent superoxide dismutase that has been well-characterized on the basis of kinetics and mechanistic studies; however, prior to our studies, its electronic structure had yet to be examined. This paper details our initial characterization of Fe(dapsox) in both its reduced and oxidized states, by electronic absorption (Abs) and low-temperature magnetic circular dichroism spectroscopies. Density functional theory (DFT) geometry optimizations have yielded models in good agreement with the published crystal structures. Time-dependent DFT and INDO/S-CI calculations performed on these models successfully reproduce the experimental Abs spectra and identify intense, low-energy transitions in the reduced complex (Fe(II)(H(2)dapsox)) as metal-to-ligand charge transfer transitions, suggesting the presence of π-backbonding in this complex. This backbonding, along, with the proton uptake accompanying metal ion reduction, provides a compelling mechanism by which the metal-centered redox potential is correctly tuned for catalytic superoxide disproportionation.

Surface Patterning of Benzenecarboxylic Acids: Influence of Structure, Solvent, and Concentration on Molecular Self-Assembly

We investigated the molecular self-assembly of pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), and 1,3,5-benzenetriacetic acid at the liquid/graphite interface to assess how the number and orientation of carboxylic acid groups modulate network formation. In addition, we studied the roles solvent composition and solution concentration play in the self-assembly of pyromellitic acid and trimellitic acid by investigating each in various alkanoic acid/alkanol solvents and solvent mixtures under saturated and diluted conditions. For pyromellitic acid, three distinct, ordered monolayer structures were observed, depending on the solvent type and solution concentration. Trimellitic acid was observed to form highly disordered monolayers due to the molecule’s inherent asymmetry, whereas high-symmetry networks are observed from the symmetric building block pyromellitic acid. No solvent or concentration effects were observed for trimellitic acid monolayers. Self-assembly was not observed for 1,3,5-benzenetriacetic acid, likely due to an insufficient adsorption energy and difficulty in forming extended hydrogen-bonded networks because of its nonplanar molecular structure. Density functional theory geometry optimizations and relaxed potential energy surface scans were used to explore the conformational preferences of isolated analogue molecules, benzoic acid and phthalic acid (1,2-benzenedicarboxylic acid), providing a qualitative picture of surface adsorption and network formation. The observed network structures and solvent/concentration effects are rationalized using basic principles of thermodynamics and equilibrium.

Patupilone and Ixabepilone: The Effect of a Point Structural Change on the Exo–Endo Conformational Profile

The natural product patupilone (epothilone B) and its synthetic aza-analogue, ixabepilone, are effective agents against a broad range of human cancers. A detailed conformational analysis was conducted on the basis of single-point MP2 energy calculations for density functional theory (DFT) geometries at the MP2/6-31+G(d,p)//B3LYP/6-31+G(d,p) level. In a vacuum, patupilone exclusively adopts compact exo conformations due to short, near-linear hydrogen bonding between the 3-hydroxyl group and the side-chain thiazole. In contrast, ixabepilone can be described as a competitive mixture of exo and endo conformers with a large population of the above-mentioned compact exo conformations. The stability of the endo form is consistent with the cooperativity of hydrogen bonds. The relative energies of some patupilone and ixabepilone conformers were found to be sensitive to solvent effects within the integral equation formalism polarizable continuum model (IEF-PCM). This study contributes to a better understanding of the important structural features of patupilone and ixabepilone. This conformational analysis lends support to previous observations concerning their different pharmaceutical profiles.

Computational studies of graphene growth mechanisms

Density functional theory (DFT) and semiempirical tight-binding (TB) methods have been used to study the mechanism of graphene growth in the presence and absence of a catalytic surface. Both DFT and TB geometry optimized structures relevant to graphene growth show that the minimum energy growth mechanism is via the sequential addition of carbon hexagons at the edge of the graphene sheet. Monte Carlo (MC) simulations based on the TB model show that defect-free graphene sheets can be grown provided one has the proper combination of temperature, chemical potential, and addition rate. In this work, growth of perfect graphene structures has been simulated at the atomic level. Comparison of the growth mechanism in the absence and presence of a nickel catalyst surface shows that the catalyst (i) allows for adsorption of carbon atoms at surface and subsurface sites, (ii) enables formation of long, stable strings of carbon atoms, and (iii) stabilizes small flakes of graphene that can act as precursors to subsequent growth.

Structural Similarities in Dinuclear, Tetranuclear, and Pentanuclear Nickel Silyl and Silylene Complexes Obtained via Si–H and Si–C Activation

The reactions of (iPr3P)2Ni0 precursors with Ph2SiHCl, Ph2SiH2, PhSiH3, and Ph3SiH provide mononuclear, dinuclear, tetranuclear, and pentanuclear complexes with silyl and silylene ligands. Reaction of the dinuclear Ni(0) dinitrogen complex [(iPr3P)2Ni]2(μ-η1:η1-N2) with Ph2SiHCl afforded the thermally sensitive mononuclear complex (iPr3P)2Ni(H)SiClPh2 (1), which displays considerable hydridic character in the Ni–H–Si interaction. This species thermally converts to the dinuclear complex [(iPr3P)Ni(μ-SiHPh2)]2 (2), where the silyl ligand bridges via an agostic Si–H interaction. Alternate higher-yield routes to 2 include the rapid room-temperature reaction of Ph2SiH2 with [(iPr3P)2Ni]2(μ-η1:η1-N2) and the reaction of Ph2SiH2 with Ni(1,5-cyclooctadiene)2 and iPr3P at elevated temperatures. Double Si–H activations are observed in the reaction of PhSiH3 with [(iPr3P)2Ni]2(μ-η1:η1-N2), which provides the tetranuclear C3-symmetric complex (iPr3P)Ni[(iPr3P)Ni(μ3-SiHPh)]3 (3) as the major product and the pentanuclear S4-symmetric complex Ni[(iPr3P)Ni(μ3-SiHPh)]4 (4) as a minor product. Density functional theory (DFT) geometry optimizations of model complexes support the presence of agostic Ni–H–Si interactions within the tetra- and pentanuclear cores of 3 and 4. The reaction of Ph3SiH with [(iPr3P)2Ni]2(μ-η1:η1-N2) results in Si–C bond cleavage to provide the asymmetric dinuclear complex [(iPr3P)2Ni]2(μ-C6H5)(μ-SiHPh2) (5), where the phenyl moiety is asymmetrically bridging. Complexes 2–5 all display similar coordination environments at one of the nickel centers, suggestive of formal oxidation state assignments of Ni(III)–Ni(I) in tetranuclear 3 and Ni(IV)–Ni(I) in pentanuclear 4.

Biomolecular Chemistry of Isopropyl Fibrates

Isopropyl 2-[4-(4-chlorobenzoyl)-phenoxy]-2-methylpropanoic acid and isopropyl 2-(4-chlorophenoxy)-2-methylpropanoate, also known as fenofibrate and isopropyl (iPr) clofibrate, are hypolipidemic agents of the fibrate family. In a previously reported triclinic structure of fenofibrate (polymorph I), the methyl groups of the iPr moiety are located symmetrically about the carboxylate group. We report a new monoclinic form (polymorph II) of fenofibrate and a first structural description of iPr clofibrate, and in these the methyl groups are placed asymmetrically about the carboxylate group. In particular, the dihedral (torsion) angle between the hydrogen atom on the secondary C and the C atom of the carboxyl group makes a 2.74° angle about the ester O···C bond in the symmetric fenofibrate structure of polymorph I, whereas the same dihedral angle is 45.94° in polymorph II and -30.9° in the crystal structure of iPr clofibrate. Gas-phase density functional theory (DFT) geometry minimizations of fenofibrate and iPr clofibrate result in lowest energy conformations for both molecules with a value of about ±30° for this same angle between the OC-O-C plane and the C-H bond of the iPr group. A survey of crystal structures containing an iPr ester group reveals that the asymmetric conformation is predominant. Although the hydrogen atom on the secondary C atom of the iPr group is located at a comparable distance from the carbonyl oxygen in the symmetric and asymmetric fenofibrate (2.52 and 2.28 Å) and the iPr clofibrate (2.36 Å) structures, this hydrogen atom participates in a puckered five-membered ring arrangement in the latter two that is unlike the planar arrangement found in symmetric fenofibrate (polymorph I). Polar molecular surface area values indicate fenofibrate and iPr clofibrate are less able to act as acceptors of hydrogen bonds than their corresponding acid derivatives. Surface area calculations show that dynamic polar molecular surface area values of the iPr esters of the fibrates are lower than those of their acids, implying that the fibrates have better membrane permeability and a higher absorbability and hence are better prodrugs when these agents need to be orally administered.

Synthesis, characterization and DFT study of 4H-benzo[h]chromene derivatives

Abstract Interaction of 4-methoxy-1-naphthol (1) with α-cyano-p-chlorocinnamonitrile (2a) and ethyl α-cyano-p-chlorocinnamate (2b) provided 2-amino-4-(4-chlorophenyl)-6-methoxy-4H-benzo[h]chromene-3-carbonitrile (3a) and ethyl 2-amino-4-(4-chlorophenyl)-6-methoxy-4H-benzo[h]chromene-3-carboxylate (3b), respectively. Structures of these compounds were established on the basis of IR, UV, 1H NMR, 13C NMR, 13C NMR-DEPT and MS data. Moreover, imino tautomer (3b′) has been designed. Using density functional theory geometries have been optimized at B3LYP/6-31G* level of theory, the absorption spectra has been computed by using time dependant density functional theory at TD-B3LYP/6-31G* level of theory. Moreover, the absorption spectra in solvents have been computed and compared with experimental data. The highest occupied molecular orbitals, lowest unoccupied molecular orbitals and HOMO–LUMO energy gap of studied systems have been discussed.

DFT study of Sb(III) and Sb(V) adsorption and heterogeneous oxidation on hydrated oxide surfaces

This study reports on density functional theory (DFT) modeling of antimony adsorption at model environmental interfaces. Both Sb(III) and Sb(V) surface complexes were studied on hydrated alumina and hematite, at varying adsorption sites and with varying distal Sb coordination. We calculate the DFT reaction energies of a number of hypothetical heterogeneous interconversion reactions of Sb surface complexes with gas-phase water and oxygen, which predict that an octahedral Sb(V) surface complex is overall the most favorable. Additionally, the results suggest that several different heterogeneous pathways starting from distinct metastable Sb surface complexes are possible, including an antimonyl (SbO) surface complex. A total of 28 Sb surface complexes are found through DFT geometry optimizations, the structural and energetic details of which are reported to guide future experimental studies and to form a basis for ongoing theoretical work including dynamic simulations.

Electronic Structure and Thermochemical Properties of Small Neutral and Cationic Lithium Clusters and Boron-Doped Lithium Clusters: Lin0/+ and LinB0/+ (n = 1–8)

The stability, electronic structure, and thermochemical properties of the pure Li(n) and boron-doped Li(n)B (n = 1-8) clusters in both neutral and cationic states are studied using electronic structure methods. The global equilibrium structures are established, and their heats of formation are evaluated using the G3B3 and CCSD(T)/CBS methods based on the density functional theory geometries. Theoretical adiabatic ionization energies (IE(a)) for the Li(n) clusters are in good agreement with experiment: Li(2) (G3B3, 5.21 eV; CCSD(T), 5.14 eV; expt, 5.1127 ± 0.0003 eV), Li(3) (4.16, 4.11, 4.08 ± 0.10), Li(4) (4.76, 4.68, 4.70 ± 0.05), Li(5) (4.11, 4.06, 4.02 ± 0.10), Li(6) (4.46, 4.32, 4.20 ± 0.10), Li(7) (4.07, 3.99, 3.94 ± 0.10), and Li(8) (4.49, 4.31, 4.16 ± 0.10). The Li(4) experimental IE(a) has been revised on the basis of the Franck-Condon simulations. Species Li(5)B, Li(6)B(+), Li(7)B, and Li(8)B(+) exhibit high stability as compared to their neighbors, which can be understood by considering the magic numbers of the phenomenological shell model (PSM).

A New Organic–Inorganic Hybrid Oxyfluorotitanate [Hgua]2·(Ti5O5F12) as a Transparent UV Filter

A new generation UV absorber is obtained by microwave-heating-assisted hydrothermal synthesis: [Hgua](2)·(Ti(5)O(5)F(12)). The structure of this hybrid titanium(IV) oxyfluoride is ab initio determined from powder X-ray data by combining a direct space method, Rietveld refinement [orthorhombic, Cmm2, a = 22.410(1) Å, b = 11.191(1) Å, c = 3.802(1) Å], and density functional theory geometry optimization. The three-dimensional network is built up from infinite inorganic layers (∞)(Ti(5)O(5)F(12)) separated by guanidinium cations. The theoretical optical gap (3.2 eV) estimated from density of state calculations is in good agreement with the experimental gap (3.3 eV) obtained by UV-vis diffuse reflectivity. The optical absorption is mainly due to O(2p) → Ti(3d) and F(2p) → Ti(3d) transitions at higher energies. The refraction index is low in the visible range (n ≈ 1.9) compared to that of TiO(2) and, consequently, [Hgua](2)·(Ti(5)O(5)F(12)) shows a good transparency adapted to UV shielding. Under UV irradiation at 254 nm for 40 h, the white microcrystalline powder turns to light purple-gray. This color change is caused by the reduction of Ti(IV) to Ti(III), confirmed by magnetic measurements.

How to find an optimum cluster size through topological site properties: MoSxmodel clusters

Computational investigations in catalysis frequently use model clusters to represent realistically the catalyst and its reaction sites. Detailed knowledge of the molecular charge, thus electronic density, of a cluster would then allow physical and chemical insights of properties and can provide a procedure to establish their optimum size for catalyst studies. For this purpose, an approach is suggested to study model clusters based on the distributed multipole analysis (DMA) of molecular charge properties. After full density functional theory (DFT) geometry optimization of each cluster, DMA computed from the converged DFT one-electron density matrix allowed the partition of the corresponding cluster charge distribution into monopole, dipole, and quadrupole moments on the atomic sites. The procedure was applied to MoS2 model clusters Mo10S18, Mo12S26, Mo16S32, Mo23S48, and Mo27S54. This analysis provided detailed features of the charge distribution of each cluster, focused on the 1010 (Mo or metallic edge) and 1010 (sulfur edge) active planes. Properties of the Mo27S54 cluster, including the formation of HDS active surfaces, were extensively discussed. The effect of cluster size on the site charge distribution properties of both planes was evaluated. The results showed that the Mo16S32 cluster can adequately model both active planes of real size Mo27S54. These results can guide future computational studies of MoS2 catalytic processes. Furthermore, this approach is of general applicability.

Efficiency of random search procedures along the silicon cluster series: Sin (n = 5–10, 15, and 20)

The efficiency of the simplest isomeric search procedure consisting in random generation of sets of atomic coordinates followed by density functional theory geometry optimization is tested on the silicon cluster series (Si(5-10, 15, 20)). Criteria such as yield, isomer distributions and recurrences are used to clearly establish the performance of the approach with respect to increasing cluster size. The elimination of unphysical candidate structures and the use of distinct box shapes and theoretical levels are also investigated. For the smaller Si(n) (n=5-10) clusters, the generation of random coordinates within a spherical box is found to offer a reasonable alternative to more complex algorithms by allowing straightforward identification of every known low-lying local minima. The simple stochastic search of larger clusters (i.e. Si(15) and Si(20)) is however complicated by the exponentially increasing number of both low- and high-lying minima leading to rather arbitrary and non-comprehensive results.

Reaction Mechanism of Monoethanolamine with CO2 in Aqueous Solution from Molecular Modeling

We present a theoretical study of the reaction mechanism of monoethanolamine (MEA) with CO₂ in an aqueous solution. We have used molecular orbital reaction pathway calculations to compute reaction free energy landscapes for the reaction steps involved in the formation of carbamic acids and carbamates. We have used the conductor-like polarizable continuum model to calculate reactant, product, and transition state geometries and vibrational frequencies within density functional theory (DFT). We have also computed single point energies for all stationary structures using a coupled cluster approach with singles, doubles, and perturbational triple excitations using the DFT geometries. Our calculations indicate that a two-step reaction mechanism that proceeds via a zwitterion intermediate to form carbamate is the most favorable reaction channel. The first step, leading to formation of the zwitterion, is found to be rate-determining, and the activation free energies are 12.0 (10.2) and 11.3 (9.6) kcal/mol using Pauling (Bondi) radii within the CPCM model at the CCSD(T)/6-311++G(d,p) and CCSD(T)/6-311++G(2df,2p) levels of theory, respectively, using geometries and vibrational frequencies obtained at the B3LYP/6-311++G(d,p) level of theory. These results are in reasonable agreement with the experimental value of about 12 kcal/mol. The second step is an acid-base reaction between a zwitterion and MEA. We have developed a microkinetic model to estimate the effective reaction order at intermediate concentrations. Our model predicts an equilibrium concentration for the zwitterion on the order of 10⁻¹¹ mol/L, which explains why the existence of the zwitterion intermediate has never been detected experimentally. The effective reaction order from our model is close to unity, also in agreement with experiments. Complementary ab initio QM/MM molecular dynamics simulations with umbrella sampling have been carried out to determine the free energy profiles of zwitterion formation and proton transfer in solution; the results confirm that the formation of the zwitterion is rate-determining.

Computational investigations of the stereoselectivities of proline-related catalysts for aldol reactions☆

Computational investigation of the aldol reaction of benzaldehyde with acetone catalyzed by various proline derivatives and 2-azetidine carboxylic acid reveal the origins of stereoselectivities of these reactions. Structural differences between catalysts and transition states were analyzed with density functional theory geometries in order to establish the key factors that will help in the design of new catalysts.

DFT and GEGA genetic algorithm optimized structures of Cun ν (ν=±1,0,2; n=3-13) clusters

We report a study on small copper clusters $\text{Cu}_n^{\nu}$ (ν= ±1,0,2; n=3-13) where the minimum energy structures were computed through a joint gradient embedded genetic algorithm (GEGA) technique, and further density functional theory (DFT) geometry reoptimization of the best GEGA cluster structures for each size and charge. Our results are compared to previous ab initio and DFT calculations, when available in the literature, and it is shown than a number of never reported structures for some clusters have been found. From an extensive calibration of some of the DFT commonly used approximate functionals and basis sets, a discussion on its performance and efficiency for Cu cluster calculations is provided. All GEGA found structures are subject to a second step DFT reoptimization process, at the final reported level of theory, BLYP/6-311+G(d), and it is observed that the symmetry found initially by GEGA for almost all of the 66 clusters studied is kept during the DFT reoptimization, which shows the reliability of the initial search algorithm employed. Several geometry-related-properties of these clusters are discussed and compared with some results available in the literature.

Synthesis, regioselective hydrogenolysis, partial hydrogenation, and conformational study of dioxane and dioxolane-type (9′-anthracenyl)methylene acetals of sugars

Dioxane-type (9′-anthracenyl)methylene acetal of methyl 2,3-di-O-methyl-α-d-glucopyranoside was cleaved with LiAlH4/AlCl3 (3:1) or with Na(CN)BH3–HCl regioselectively to provide the 4- or 6-O-(9′-anthracenyl)methyl ether, respectively. Hydrogenolytic reaction of the exo and endo isomers of dioxolane-type acetals proved to be directed by the configuration of the acetalic carbon as well as by the intramolecular participation of the adjacent-free hydroxyl; ring-opening reaction of the endo isomer of the methyl 2,3-O-(9′-anthracenyl)methylene-α-l-rhamnopyranoside took place with complete selectivity resulting in the axial (9′-anthracenyl)methyl ether, whereas a 1:1 mixture of the axial and equatorial ethers was formed upon the same reaction of the exo isomer. Catalytic hydrogenation of the sugar acetals resulted in (9′,10′-dihydro-9′-anthracenyl)methylene derivatives without affecting the acetalic center. High-temperature molecular dynamics simulations and DFT (Density Functional Theory) geometry optimizations were carried out to study the conformation of the dioxane-type (9′,10′-dihydro-9′-anthracenyl)methylene acetal.