Benzaldehyde Molecules Research Articles

CH activations in aldehydes in reactions with Ru5(μ5-C)(CO)15

The reaction of Ru5(μ5-C)(CO)15, 1 with benzaldehyde yielded two new pentaruthenium carbido cluster compounds: Ru5(μ5-C)(CO)14[η2-O=C(H)C6H4](μ-H), 2 and Ru5(μ5-C)(CO)14(μ-η2-O=CPh)(μ-H), 3 containing open Ru5C cluster complexes formed by the activation of two different C-H bonds of the benzaldehyde molecule. Compound 2 contains a chelating, ortho-metallated benzaldehyde ligand coordinated to an open Ru5C cluster that is coordinated by the aldehyde oxygen atom and one of the ortho-positioned carbon atoms of the phenyl ring that was formed by loss of a CO ligand and an oxidative addition of the ortho-C-H bond of the phenyl ring to the metal atom. Compound 3 is an isomer of 2 that contains an O=C-coordinated, η2-bridging benzoyl ligand across the open edge of the Ru5C cluster formed by C-H activation at the aldehyde formyl group. The reaction of 1 with trans-cinnamaldehyde yielded two complexes: Ru5(μ5-C)(CO)14[η2-O=C(H)CH=CPh](μ-H), 4 and Ru5(μ5-C)(CO)14[μ-η2-O=CC(H) = C(H)Ph](μ-H), 5. Compound 4 contains an open Ru5 cluster with a chelating cinnamoyl ligand formed by coordination of the aldehyde oxygen atom and the β–carbon atom of the alkene double bond formed by a C-H activation at the alkene atom. Compound 5 contains a η2-bridging, O=C coordinated cinnamoyl group formed by C-H activation at the aldehyde formyl group. The reactions of 1 with furfural and 5-hydroxymethylfurfural yielded similar complexes: Ru5(μ5-C)(CO)14(μ-η2-O=CC4OH3)(μ-H), 6 and Ru5(μ5-C)(CO)14[μ-η2-O=CC4OH2(CH2OH)](μ-H), 7, respectively with each one containing bridging, O=C coordinated acyl ligand formed by C-H activation at the aldehyde formyl group. All of the new compounds were characterized by single-crystal X-ray diffraction analyses.

Dynamic Covalent Silica Nanoparticles for pH-Switchable Pickering Emulsions.

Dynamic covalent surfactants have been recently reported for preparation of pH-switchable emulsions [ Sun , D. Langmuir , 2017 , 33 , 3040 ]. In this study, dynamic covalent silica (SiO2-B) nanoparticles of switchable wettability were fabricated by a pH-responsive dynamic (covalent) imine bond between hydrophilic amino silica (SiO2-NH2) nanoparticles and hydrophobic benzaldehyde molecules. The properties of SiO2-B were characterized by Fourier transform infrared spectroscopy, elemental analysis, contact angle measurement, and ζ potential measurement. The hydrophilicity and hydrophobicity of SiO2-B were shown to be readily switchable by adjusting pH between 7.8 and 3.5. At pH 7.8, SiO2-B was partially hydrophobic and adsorbed at oil-water interface to stabilize O/W Pickering emulsions, which were characterized by electrical conductivity, optical microscopy, and confocal laser scanning microscopy. Upon lowering the pH to 3.5, the dynamic covalent bond is dissociated to convert partially hydrophobic SiO2-B into highly hydrophilic SiO2-NH2 and surface-inactive benzaldehyde. Both of them desorb from oil-water interface, resulting in a rapid oil-water separation of the Pickering emulsions. Alternating stabilization and phase separation of the Pickering emulsions over 3 cycles were demonstrated by adjusting the pH. The pH-switchable Pickering emulsions show great potential in application to effective oil-water separation of emulsions.

Role of gold nanocolloids on the photostability of 2-hydroxy-5-methyl benzaldehyde molecule and evidence of excited state intramolecular proton transfer process aided by DFT, non-adiabatic Ab Initio molecular dynamics simulations

The role of gold nanocolloids (AuNCs) on the photostability of 2-hydroxy-5-methyl benzaldehyde (HMBZ) molecule under UV exposures has been investigated using UV–vis absorption and fluorescence spectroscopic techniques. The experimental observations indicate the prominent role of AuNC towards controlling the photoproduct formations and rupture of intramolecular hydrogen bond (IHB) in the ‘CE’ conformeric form of the molecule. The rationale behind the experimental observations has been suggested to be due to the absorption of incident UV radiations by the nanoparticles, leaving behind only insignificant fraction of it for inducing photodegradation of HMBZ molecule. The photophysical behaviors of HMBZ molecule in different solvents and in varied pH media are also explicitly studied for the first time. Evidences of excited state intramolecular proton transfer (ESIPT) species of the molecule are estimated from the experimental observations aided by non-adiabatic Ab Initio molecular dynamics and density functional theory (DFT) calculations.

Synthesis, characterization, and antimicrobial activity of chitosan hydrazide derivative

ABSTRACTA series of modified chitosan derivatives 1–4 has been synthesized. Modification process of chitosan was achieved through a sequence of four reactions starting by protection of its amino group with benzaldehyde (derivative 1), followed by reaction with epichlorohydrine (derivative 2), then reaction with benzhydrazide (derivative 3), and finally restoring the free amino groups on the chitosan by removing of benzaldehyde molecules (derivative 4). These four derivatives were characterized by elemental analyses, FTIR, and X-ray. The four chitosan derivatives showed better antibacterial and antifungal activities than that of chitosan. Derivative 4 exhibited the highest antimicrobial activity relative to the other derivatives.

Molecular structure, vibrational spectral assignments (FT-IR and FT-RAMAN), NMR, NBO, HOMO-LUMO and NLO properties of O-methoxybenzaldehyde based on DFT calculations

Fourier transform – Infra red (FT-IR) and Fourier transform – Raman (FT-Raman) spectroscopic techniques have been carried out to analyze O-methoxy benzaldehyde (OMB) molecule. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT). The vibrational analysis of stable isomer of OMB has been carried out by FT-IR and FT-Raman in combination with theoretical method simultaneously. The first-order hyperpolarizability and the anisotropy polarizability invariant were computed by DFT method. The atomic charges, hardness, softness, ionization potential, electronegativity, HOMO-LUMO energies, and electrophilicity index have been calculated. The 13C and 1H Nuclear magnetic resonance (NMR) have also been obtained by GIAO method. Molecular electronic potential (MEP) has been calculated by the DFT calculation method. Electronic excitation energies, oscillator strength and excited states characteristics were computed by the closed-shell singlet calculation method.

Insight into the cocatalyst effect of 4A molecular sieve on Sn(II) porphyrin-catalyzed B–V oxidation of cyclohexanone

The cocatalyst effect of 4A molecular sieve (4A-MS) on the catalytic activity of tin(II) meso-tetraphenylporphyrin (SnTPP) was investigated in the aerobic Baeyer–Villiger oxidation of cyclohexanone in the presence of benzaldehyde as reductant, remarkable enhancement on the yield of ɛ-caprolactone was achieved (from 21% to 83%). The in situ Raman spectroscopy confirmed the interaction between 4A-MS and the carbonyl group of benzaldehyde and cyclohexanone molecules. The major role of 4A-MS was to active cyclohexanone and benzaldehyde molecules by the coordination between the oxygen atom of carbonyl group and the Lewis acid site of 4A-MS. The activated benzaldehyde tended to combine dioxygen easily, which resulted in the accelerated generation rate of peroxybenzoic acid and the high-valent Sn porphyrin (PorSnIVO). Accordingly, the slow generation rate of Criegee adduct intermediate by the reaction between cyclohexanone and high-valent Sn porphyrin was accelerated. A cocatalytic mechanism involving the activated cyclohexanone and benzaldehyde was proposed.

A class of linker free amphiphilic PEG grafted polymer support for linear and cyclic peptides

PEG grafted (PEG400 and PEG1500), highly hydrophobic/hydrophilic balanced polymeric Schiff base dendron resins were synthesized by the reaction between diethylenetriamine and benzaldehyde molecules and characterized. The usefulness of the resins was demonstrated by synthesizing biologically significant linear as well as disulfide classes of endothelin peptides in high yields and purities.

Molecular mechanism of micellar catalysis of cross aldol reaction: Effect of surfactant chain length and surfactant concentration

The importance of alkyl chain length and concentration of quaternary ammonium surfactants (QAS) in the micellar catalysis of cross aldol reaction was investigated. The NaOH-micellar system catalyzed aldol reaction of benzaldehyde and cyclohexanone to α,α′-dibenzylidene cyclohexanone (di condensation/desired product) over mono condensation product was used as model reaction for this study. The C16QAS micellar system (QAS with n-hexadecyl group) gave highest cyclohexanone conversion (90%) to desired product (82%) showing that C16QAS micellar system possesses optimum properties and/or microenvironment for this reaction. Furthermore, the micellar system with high surfactant concentration (C16QAS; >150mM) made the reaction faster giving >99% conversion to selectively desired product (>99%) within 30min The large interface created by C16QAS micelles in the aqueous medium at high surfactant concentration makes the reaction faster by facilitating the interaction of hydrophobic reactants and water soluble catalyst (OH− ions). The activation of benzaldehyde molecules, their localization preferably near the interface and stabilization of enolate ions (reactive intermediates) by micellar system at high surfactant concentration were observed to be promoting the cross reaction selectively to the desired product.

Water- and Moisture-sensitive Polymeric Releasing System by Hydrolysis of Acetal Moieties Coexisting with Acidic Units

Abstract A methacrylate monomer containing acetal and benzaldehyde-derived moieties was copolymerized with a sulfonic acid monomer. The copolymer underwent hydrolysis by neighboring effects to release benzaldehyde molecules upon contact with pure water and moisture in aqueous DMF solution and in the solid state.

Conformational stability and ligand binding properties of BldR, a member of the MarR family, from Sulfolobus solfataricus

The multiple antibiotic resistance regulators (MarR) constitute a family of ligand-responsive transcriptional regulators ubiquitous among the bacterial and archaeal domains. BldR, an archaeal MarR member characterized from the hyperthermophilic crenarchaeon Sulfolobus solfataricus regulates its own expression and that of an alcohol dehydrogenase gene by binding to sequences in their promoters and responding to benzaldehyde as the effector molecule.In this study we assessed the thermodynamic stability of the protein BldR and its binding with benzaldehyde through biophysical measurements. The temperature- and denaturant-induced unfolding experiments, performed by means of circular dichroism (CD) and differential scanning calorimetry (DSC), showed that BldR has an extremely high thermal stability (Td=108.9°C) and a remarkable resistance against GuHCl (Cm=5.3M at 25°C). The unfolding Gibbs energy, ΔdG (H2O), calculated by the linear extrapolation model from GuHCl-induced unfolding equilibrium curve, is 72.2kJmol−1.ITC binding experiments showed that four benzaldehyde molecules bind to one BldR dimer with a binding constant Kb of 7.5·105M−1, being the binding entropically driven. ITC, CD and fluorescence results are consistent with a conformational change induced by benzaldehyde binding, further proving that this molecule is a specific effector for BldR modulating its DNA binding activity.

Liquid–liquid equilibria for benzaldehyde + n-alkane mixtures and characterization of benzaldehyde + hydrocarbon systems in terms of DISQUAC

Liquid–liquid equilibrium (LLE) temperatures have been determined for benzaldehyde+CH3(CH2)nCH3 (n=8, 10,12,14) mixtures by means of the opalescence method using a laser scattering technique. All the solutions show an upper critical solution temperature (UCST), which increases almost linearly with n. Benzaldehyde+benzene, or+alkyl-benzene, or+alkane mixtures have been treated in terms of the group contribution model DISQUAC. The corresponding interaction parameters for the contacts formyl/aromatic, formyl/aliphatic, formyl/c-CH2 are reported. The former are entirely dispersive; the remainder contacts are characterized by both dispersive and quasichemical interaction parameters. The model correctly describes excess molar enthalpies, HmE, and the phase equilibrium diagrams, liquid–liquid, vapour–liquid (VLE) and solid–liquid (SLE) of the investigated solutions, over a wide range of temperature using the same set of interaction parameters. Complex phase diagrams including simultaneous LLE and SLE are also well represented by DISQUAC. It is shown that interactions between benzaldehyde and an aromatic hydrocarbon are mainly dispersive, and that those between benzaldehyde molecules in alkane solutions are of dipolar type.

Positional selectivity of reversible azomethine condensation reactions at solid/liquid interfaces leading to supramolecule formation

We used in situ scanning tunneling microscopy to investigate the formation of two-dimensional supramolecules by means of reversible azomethine condensation reactions between aqueous 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and terephthaldicarboxaldehyde (TPA) or benzaldehyde (BA) at the solid/liquid interface of an iodine-modified Au(111) surface. A nanomesh and a close-packed array were formed by the reaction of TAPP with the dicarboxaldehyde. Formation of these structures was driven by Schiff base (azomethine) bonding and simultaneous self-assembly controlled by adsorption and condensation equilibria. Surface cross coupling between TAPP and the monocarboxaldehyde (BA) formed highly ordered adlayers consisting solely of TAPP symmetrically disubstituted with two BA molecules attached at diagonally opposite corners. The position selectivity was achieved through simultaneous coupling reaction equilibria and the thermodynamic self-assembly.

Hydrogen bonds and antiviral activity of benzaldehyde derivatives

We have obtained the Fourier transform IR spectra of solutions of benzaldehyde derivatives having different antiviral activities against a herpes virus. We observe a correlation between the presence of hydrogen bonds in the benzaldehyde molecules and the appearance of antiviral properties in the compounds. For compounds having antiviral activity, we have obtained spectral data suggesting the existence of hydrogen bonds of the type C=O⋅⋅⋅H–O and O–H⋅⋅⋅O in the molecules. When the hydrogen atom in the hydroxyl groups are replaced by a methyl group, no intramolecular hydrogen bonds are formed and the compounds lose their antiviral activity.

IR spectra of benzaldehyde and its derivatives in different aggregate states

We have measured the IR Fourier-transform spectra of biologically active benzaldehyde and its derivatives in the gas and liquid phases. For compounds of this class, the role played by C=O, OH, and CH groups in intra- and intermolecular has been analyzed. We have revealed spectral features that characterize the participation of C=O groups of unsubstituted benzaldehyde molecules in the occurrence of intermolecular hydrogen bonds C=O...H-C with the formation of molecular dimers of different types. For 2-hydroxybenzaldehyde molecules, spectral data have been obtained that are indicative of the occurrence of intramolecular hydrogen bonds of the C=O...H-C type in solutions. In 2-methoxybenzaldehyde molecules, no intramolecular hydrogen bonds have been observed.

Zeolite-immobilized Mn(III), Fe(III) and Co(III) complexes with 5,10,15,20-tetra(4-methoxyphenyl)porphyrin as heterogeneous catalysts for the epoxidation of (R)-(+)-limonene: synthesis, characterization and catalytic activity

Nanodimensional pores of metal-exchanged zeolite Y containing 5,10,15,20-tetra(4-methoxyphenyl)porphyrin have been prepared by the template “ship-in-a-bottle” method. This approach requires four pyrrole molecules and four 4-methoxy benzaldehyde molecules to diffuse into the pores of FeIII, MnIII and CoIII-exchanged zeolite Y. The host–guest nanocomposite materials have been applied to catalyze the epoxidation of (R)-(+)-limonene, using H2O2/ammonium acetate, at a defined temperature and atmospheric pressure. The encapsulated iron(III) complex is catalytically very efficient as compared to manganese(III) and cobalt(III) complexes for the partial epoxidation of (R)-(+)-limonene and is stable to be recycled without much deterioration. All catalytic systems have been characterized by UV/Vis diffuse reflectance spectroscopic, X-ray diffraction, BET, scanning electron microscopy and energy dispersive X-ray spectrometry analyses to confirm the immobilization of complexes.

Reactions of Verbenol Epoxide with Aromatic Aldehydes Containing Hydroxy or Methoxy Groups in the Presence of Montmorillonite Clay

AbstractThe reactions of (−)‐cis‐verbenol epoxide with a number of aromatic aldehydes containing OH and/or MeO groups in the presence of montmorillonite K10 clay have been studied. Several new O‐containing heterocyclic compounds with different frameworks, including compounds with a previously unknown octahydro‐2H‐4,6‐(epoxymethano)chromene framework, have been synthesized. Introduction of one donor substituent in the benzaldehyde molecule led to a decrease in the total yield of intermolecular by formed products, while the introduction of two and more substituents led to an increase in the yield of these products.

Ab initio and DFT study of the static dipole (hyper)polarizabilities of benzaldehyde and thio-benzaldehyde molecules in gas phase

The results of ab initio and density functional theory DFT calculations of dipole moments and electronic contributions to static dipole (hyper)polarizabilities of benzaldehyde and thiobenzaldehyde molecules in gas phase are presented. These properties were evaluated at the SCF, MP2, MP4 and DFT (B3LYP) levels of theory with a selection of basis sets that include polarization and diffuse functions on the C, O, S and H atoms: 6-31+G(d,p) (A), 6-311++G(3d,3p) (B), 6-31+G(d*,p) (C) and the Sadlej (D) basis sets, using HF/A, MP2/A and B3LYP/A optimized geometries under the Cs symmetry restriction. The C basis set has been optimized in terms of the maxima second hyperpolarizability at HF level. Both MP2 and MP4 methods, performed at full electron configuration, have shown to perform well in the calculation of such properties. Considering the basis sets effects, the impact of the electron correlation in the (hyper)polarizabilities of these molecules is analyzed systematically in terms of the differences between MP2 and MP4 perturbation theory and those from DFT(B3LYP) methods. The effects of substitution of the C=S fragment by the C=O group in the benzaldehyde molecule, giving the formation of thiobenzaldehyde, lead to enhanced results of nonlinear optical properties in terms of their first (β) and second hyperpolarizability (γ), that shown to be higher than those for para-Nitroaniline molecules. In fact, thiobenzaldehyde exhibit significant values of nonlinear optical properties which make this chromophore a prospective building block for nonlinear optical materials.

Adsorption of Benzaldehyde at the Surface of Ice, Studied by Experimental Method and Computer Simulation

Adsorption study of benzaldehyde on ice surfaces is performed by combining experimental and theoretical approaches. The experiments are conducted over the temperature range 233-253 K using a coated wall flow tube coupled to a mass spectrometric detector. Besides the experimental way, the adsorption isotherm is also determined by performing a set of grand canonical Monte Carlo simulations at 233 K. The experimental and calculated adsorption isotherms show a very good agreement within the corresponding errors. Besides, both experimental and theoretical studies permit us to derive the enthalpy of adsorption of benzaldehyde on ice surfaces DeltaH(ads), which are in excellent agreement: DeltaH(ads) = -61.4 +/- 9.7 kJ/mol (experimental) and DeltaH(ads) = -59.4 +/- 5.1 kJ/mol (simulation). The obtained results indicate a much stronger ability of benzaldehyde of being adsorbed at the surface of ice than that of small aliphatic aldehydes, such as formaldehyde or acetaldehyde. At low surface coverages the adsorbed molecules exclusively lie parallel with the ice surface. With increasing surface coverage, however, the increasing competition of the adsorbed molecules for the surface area to be occupied leads to the appearance of two different perpendicular orientations relative to the surface. In the first orientation, the benzaldehyde molecule turns its aldehyde group toward the ice phase, and, similarly to the molecules in the lying orientation, forms a hydrogen bond with a surface water molecule. In the other perpendicular orientation the aldehyde group turns to the vapor phase, and its O atom interacts with the delocalized pi system of the benzene ring of a nearby lying benzaldehyde molecule of the second molecular layer. In accordance with this observed scenario, the saturated adsorption layer, being stable in a roughly 1 kJ/mol broad range of chemical potentials, contains, besides the first molecular layer, also traces of the second molecular layer of adsorbed benzaldehyde.

Synthesis and Mesogenic Properties of Lipophilic and Amphiphilic Tetraphenylporphyrins

Liquid crystals, based on porphyrins, belong to the discotic mesogenes and are of considerable interest for use in optoelectronics and devices for display and storage of information. Porphyrins possess all the necessary properties for that, including synthetic versatility, thermal stability and a number of special photochemical properties. In comparison with widely studied class of phthalocyanines liquid crystals based on porphyrins have lower melting points. In this study we have synthesized homologous series of lipophilic symmetrical 5,15-di- and 5,10,15,20-tetrameso-arylsubstituted porphyrins containing long chain alkyl and acyl groups, their zinc and cobalt complexes, amphiphilic derivatives and studied their mesogenic properties. The series of 5,15-di- and 5,10,15,20-tetra-mesoarylsubstituted porphyrins differ by the quantity and the length of peripherical aliphatic substitutents, type of their attachment to the porphyrin meso-phenyl groups, nature of terminal group and presence of a metal. The chain length of lipophilic substituents was varied from C 8 to C 18 atoms. Studying of mesogenic properties has allowed us to reveal and generalize structural influence on the ability of porphyrins to form mesophases. We’ve used efficient synthetic procedures to obtain these meso-arylsubstituted porphyrins. We have suggested the new approach to the synthesis of the lipoporphyrins. According to this approach the residues of higher fatty acids and alcohols are incorporated into the molecules of benzaldehyde at the initial stages of synthesis which is followed by condensation with pyrrole. This method essentially simplifies the synthetic procedure, facilitates the purification of the target porphyrins, gives the chance to carry out synthesis in soft conditions and provides higher yields of lipoporphyrins. Synthesis of 5,15-dimeso-arylsubstituted porphyrins was carried out using dipyrrolylmethanes in 36-44% yields. 5,10,15,20-Tetra-mesoarylsubstituted porphyrins were synthesised by monopyrrole condensation in 33-45 % yields. Amphiphilic derivatives were prepared by chemical modification of periferical aliphatic residues. Zinc and cobalt complexes were obtained in 90-95% yields from porphyrin ligands. The mesomorphic behavior of the porphyrin derivatives was investigated by using optical polarizing microscopy and differential scanning calorimetry. The phase transition temperatures of all compounds in the course of heating are summarized. It has been shown that eight compounds among long chain meso-arylsubstituted porphyrins could form mesophase and exhibit thermotropic and lyotropic behaviour in nonpolar solvents. Five compounds in the series of 5,15-disubstituted and one compound among 5,10,15,20-tetra-mesoarylsubstituted porphyrins were amphotropic: the thermotropic and lyotropic mesomorphism in nonpolar solvents were observed. Two 5,10,15,20-tetra-meso-arylsubstituted porphyrins exhibited only thermotropic mesomorphism. Seven porphyrins derivatives were glassing mesogens. The mesophase in all compounds was characterized by nongeometric grain structure presumably associated with a column-type packing. As a result it has been established that discotic symmetrical long chain meso-arylsubstituted porphyrins exhibit thermotropic and lyotropic behaviour in nonpolar solvents, some of them are glassing mesogens. It is obvious, the mesophase range and glassing properties of these porphyrins are influenced, first of all, by the quantity and the chain length of lipophilic substituents, and also by the type of their attachment to the porphyrin meso-phenyl groups. We have shown, that replacement of donor alkoxy by acceptor alkanoyloxy groups influences on mesogenic properties of the porphyrins derivatives. Incorporation of coordinatively unsaturated metals (Zn II and Co II ) increases the number of mesogenic porphyrins derivatives in the series of 5,15-disubstituted porphyrins and considerably changes mesogenic properties in comparison with corresponding ligands. It has been shown, that liquid crystalline properties in the case of 5,15-disubstituted porphyrins with equal lengths of aliphatic substituents at the meso-positions and the corresponding metal complexes are more similar. Thus, we have expanded databank of discotic liquid crystals based on lipophilic porphyrins derivatives and their metal complexes. The mesomorphic properties of porphyrins indicate that they offer potential usage in optoelectronic field.

Water as a Clustering Agent in Photolysis and Photonucleation of Benzaldehyde Vapor

The role of water vapor in benzaldehyde photolysis and photonucleation is investigated experimentally as well as with the help of semiempirical estimation of reaction intermediates. It is shown that water molecules act as a clustering agent that brings together two benzaldehyde molecules. This mechanism may explain the experimental observation of glyoxal formation during photolysis in humid carrier gas even in the presence of oxygen, the dependence of the concentrations of glyoxal and diphenyl on water-vapor concentration, and some other unusual facts concerning minor products detected in the experiment.