Benzoic Acid Molecules Research Articles

Target therapy at buried interfaces toward efficient and stable inorganic perovskite solar cells

The enhancement of power conversion efficiency (PCE) of perovskite solar cells (PSCs) is critically affected by charge recombination induced by buried interface defects. In light of this, a simple and effective target therapy strategy has been developed by doping 4-(diphenylphosphino)benzoic acid (4DBA) molecules at the tin oxide (SnO2)/perovskite interface. The effects of 4DBA on carrier transport, perovskite growth, defect passivation, and PSCs properties were systematically investigated. It is illustrated that 4DBA molecules not only passivate oxygen vacancy (OV) defects on the SnO2 surface, enhancing the conductivity of the SnO2 film and accelerating electron transfer, but also passivate perovskite interface defects, thereby improving the quality of the perovskite film. Ultimately, the efficiency of CsPbBr3 device with 4DBA-modified buried interface increased from 8.87% to 10.78%, an improvement of 21.53%. Furthermore, the efficiency of CsPbI2Br increased from 12.83% to 14.44%, an improvement of 12.55%, further demonstrating the effectiveness and universality of this strategy. Excitingly, the unencapsulated PSCs exhibit excellent long-term stability under high relative humidity and high temperatures.

Heteroleptic Ni(II) complexes containing chelating benzoato ligand with sharp bite angle: syntheses, crystal structures, and magnetism

From the system Ni(OH)2 – 4,4′-dmbpy – HBz (HBz = benzoic acid; 4,4′-dmbpy = 4,4′-dimethyl-2,2′-bipyridine) under various experimental conditions three complexes were isolated, namely light blue [Ni(4,4′-dmbpy)(Bz)2(H2O)] (1), violet [Ni(4,4′-dmbpy)2(Bz)](Bz)·2HBz (2), and pink microcrystalline product [Ni(4,4′-dmbpy)3](Bz)2·3.5H2O (3). The crystal structures of 1 and 2 were determined, that of 2 at two temperatures (100 and 277 K). The crystal structure of 1 is formed of neutral molecules, in which the Ni(II) central atom is hexa-coordinated by one chelating diamine ligand, one chelating and one monodentate benzoato ligands, and one aqua ligand. The crystal structure of 2 is ionic and in the complex cation the Ni(II) atom is hexa-coordinated by two chelating diamine ligands and one chelating benzoato ligand. The positive charge of the complex cation is counterbalanced by a benzoate anion, and two additional molecules of benzoic acid are present in the asymmetric unit. Magnetic properties of 1 and 2 were studied in the temperature range 1.8 – 300 K and confirmed strong axial single-ion anisotropy (D/kB = -7.78 K for 1, D/kB = -6.52 K for 2) of the Ni(II) ions in line with the deformed coordination spheres of the central atoms. In addition, antiferromagnetic spin dimers of Ni(II) ions mediated by hydrogen bonds are present in 1 with exchange coupling J/kB = -2.19 K. The obtained experimental results were supported by ab initio and DFT calculations.

Molecular origin for pH-responsive wormlike micelles of zwitterionic surfactants triggered by aromatic acid derivatives

Introduction of aromatic acid derivatives (AADs) into zwitterionic surfactants is an efficient method to prepare wormlike micelles with pH-controllable viscosity; however, the coincident molecular origin of AAD/zwitterionic surfactant binary mixtures remains unclear. Herein, the self-assembly of hydroxyl derivatives of benzoic acid (BA) and cetyldimethyl betaine (BS-16) mixtures in water was systematically assessed, and various factors, such as the molecular structure, molar ratio of AAD and BS-16, and solution pH, were investigated. The structure–property relationship of AAD/BS-16 binary mixtures was established, which provided the molecular origin for the effect of AAD on micellar microstructures and the pH-induced morphological transitions. The ortho-substituted hydroxyl moiety in the BA molecule facilitated the formation of larger wormlike micelles, whereas the effect of the meta-substituted moiety was less significant. The para-substituted hydroxyl moiety in BA did not favor micellar growth. This moiety exhibited similar characteristics to the increasing hydroxyl moiety number in the AAD molecules or solution pH where the negative effects of steric hindrance and electrostatic interactions of molecules in micelles are dominant.

5+1-Heterocyclization as preparative approach for carboxy-containing triazolo[1,5-c]quinazolines with anti-inflammatory activity

Present article is devoted to the purposeful search of novel anti-inflammatory agents among carboxyl-containing partially hydrogenated [1,2,4]triazolo[1,5-с]quinazolines and products of their tandem cyclization. It has been shown that target compound’s could be obtained via interaction between [2-(3-R-1H-1,2,4-triazol-5-yl)phenyl]amines and oxo-containing carboxylic acids and their esters of various structure. The structures of synthesized compounds were verified by appropriate methods, the features of NMR-spectra patterns were discussed as well. The low predicted toxicity of obtained compounds has been estimated using in silico methods. In vivo study on the model of acute aseptic inflammation (carrageenan test) have been revealed that synthesized compounds expose anti-inflammatory activity in the range of 0.94–52.66%. 4-(2-(Ethoxycarbonyl)-5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolin-5-yl)benzoic acid has been identified as most active compound. Additionally, the effects of some (2-R-5,6-dihydro[1,2,4]triazolo[1,5-c]quinazolin-5-yl)benzoic acids (compounds 3) on the levels of key inflammatory markers have been estimated. It has been shown that studied compounds decrease the level of neutrophils, COX-2, nitrotyrosine, IL-1b, C-reactive protein and increase level of eNOS. 4-(2-(Ethoxycarbonyl)-5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolin-5-yl)benzoic acid (3.2) has been identified as compound with most expressed anti-inflammatory activity and significant effect on the levels of marker of inflammatory processes. Molecular docking study towards СОХ-1 and СОХ-2 has been conducted to substantiate possible mechanism of obtained compounds anti-inflammatory activity. It has been found that fixation of 4-(2-(ethoxycarbonyl)-5,6-dihydro-[1,2,4]triazolo[1,5-c]quinazolin-5-yl)benzoic acid (3.2) molecule in active site of enzyme is outstandingly similar to the reference ligands. The essential value of carboxylic group for presence of anti-inflammatory activity has been estimated as result of SAR-analysis. It has been found that studied class of compounds is perspective for further structural modification aimed to the creation of novel anti-inflammatory agents.

Mechanistic insights into Criegee intermediates with benzoic acid at gas-phase and air-water interface and nucleation of product

Since the detection of Criegee intermediates (CIs) in the gas phase, there has been a growing recognition of the important role of CIs in atmospheric oxidation. Further mechanistic investigations are required to fully elucidate the bimolecular reactions of CIs with atmospheric species, such as OH, RO2/HO2, and carbonyl compounds. This article primarily focused on the reactions of benzoic acid (BA) with syn- and anti- CH3CHOO (C2 CI) in both gas-phase and gas-liquid interface using density functional theory (DFT) and Born-Oppenheimer molecular dynamics (BOMD). The results reveal that the reactions of BA and anti-CH3CHOO represent the principal pathway in the gaseous phase, whereas the water-involved reactions exhibit higher energy barriers, rendering them less favorable for occurrence. At the air-water interface, the reactions of BA and C2 CI as well as the BA-catalyzed hydration take place on the picosecond scale, conforming to the stepwise mechanism. The direct reaction between BA and anti- CH3CHOO remains the main sink for C2 CI at the gas-liquid interface. Molecular dynamics (MD) simulations were employed to investigate the nucleation capabilities of the reaction products and to examine the influence of temperature and water molecules on the nucleation process. The product molecules of BA and C2 CI can form stable clusters with sulfuric acid, ammonia molecules, and water molecules within 30 ns? The nucleation ability tends to decrease with the elevation of temperature, and the presence of water molecules promotes the new particles formation (NPF). Therefore, BA and its products with CIs affect the budget of secondary organic aerosols (SOAs).

Preparation, characterization, antioxidant and antifungal activities of benzoic acid compounds grafted onto chitosan

The current study created three novel chitosan derivatives named BACS, PIBACS, and MHBACS by grafting benzoic acid (BA), p-isopropyl benzoic acid (PIBA), and m-hydroxybenzoic acid (MHBA) onto chitosan (CS). The structures of the derivatives were investigated using infrared spectroscopy (FT-IR) and nuclear magnetic resonance (13C NMR). The derivatives were discovered to be 45.06 %–60.49 % substituted using elemental analysis (EA). Based on the findings of in vitro antioxidant experiments (hydroxyl radical scavenging activity, superoxide anion radical scavenging activity, and DPPH radical scavenging activity), all of the derivatives had a higher hydroxyl radical scavenging activity than the chitosan raw material. MHBACS scavenged (31.02 ± 0.90)% of hydroxyl radicals at 0.5 mg/mL, 28.69 % more than chitosan raw. The derivatives scavenged more superoxide anion radicals than the chitosan feedstock at a particular concentration. For instance, at a test dose of 0.2 mg/mL, the scavenging rate of MHBACS on superoxide anion radicals was 7.75 % greater than that of chitosan raw materials. DPPH radical scavenging activity, on the other hand, was not as competent as chitosan feedstock. The growth rate approach was used to assess the potential of the three derivatives to inhibit the development of four phytopathogenic fungi. Chitosan derivatives have better antifungal efficacy than chitosan raw materials. PIBACS, MHBACS, BACS, and Wuyiencin inhibited Phytophthora capsici by (98.03 ± 1.95)%, (81.73 ± 1.63)%, (66.38 ± 1.81)%, and (93.01 ± 2.69)%, respectively, at 1.0 mg/mL. PIBACS had a higher inhibitory impact on Phytophthora capsici than the positive control. Based on the evidence presented above, it is reasonable to conclude that the addition of benzoic acid molecules increased the antioxidant and antifungal capabilities of chitosan.

Illumination Enhanced Crystallization and Defect Passivation for High Performance CsPbI3 Perovskite Solar Cells by Sacrificing Dye

AbstractAll‐inorganic perovskite solar cells (PSCs) have been the research focus due to their high thermal stability and proper band gap for tandem solar cells. However, their power conversion efficiency (PCE) is still lower than that of organic‐inorganic hybrid PSCs. Herein, a sacrificing dye (Rhodamine B isothiocyanate, RBITC) is developed to regulate the growth of perovskite film by in situ release of ethylammonium cations, isothiocyanate anions and benzoic acid molecules upon annealing and illumination. The ethylammonium cations can efficiently passivate surface defects. The isothiocyanate anions incorporate with uncoordinated Pb to regulate the crystallization process. The benzoic acid molecules facilitate the nucleation of the perovskite crystals. Especially, the illumination can accelerate the release of these beneficial ions/molecules to improve the quality of perovskite films further. After optimization with RBITC, a high open circuit voltage (VOC) of 1.24 V and a champion PCE of 20.95% are obtained, which are among the highest Voc and PCE values of CsPbI3 PSCs. Accordingly, the operational stability of the PSC devices is significantly improved. The results provide an efficient chemical strategy to regulate the formation of perovskite films in whole crystallization process for high performance all‐inorganic PSCs.

Connection of ssDNA to Silicon Substrate Based on a Mechano-Chemical Method.

A novel fabrication process to connect single-stranded DNA (ssDNA)to a silicon substrate based on a mechano-chemical method is proposed. In this method, the single crystal silicon substrate was mechanically scribed in a diazonium solution of benzoic acid using a diamond tip which formed silicon free radicals. These combined covalently with organic molecules of diazonium benzoic acid contained in the solution to form self-assembled films (SAMs). The SAMs were characterized and analyzed by AFM, X-ray photoelectron spectroscopy and infrared spectroscopy. The results showed that the self-assembled films were covalently connected to the silicon substrate by Si-C. In this way, a nano-level benzoic acid coupling layer was self-assembled on the scribed area of the silicon substrate. The ssDNA was further covalently connected to the silicon surface by the coupling layer. Fluorescence microscopy showed that ssDNA had been connected, and the influence of ssDNA concentration on the fixation effect was studied. The fluorescence brightness gradually increased with the gradual increase in ssDNA concentration from 5 μmol/L to 15 μmol/L, indicating that the fixed amount of ssDNA increased. However, when the concentration of ssDNA increased from 15 μmol/L to 20 μmol/L, the detected fluorescence brightness decreased, indicating that the hybridization amount decreased. The reason may be related to the spatial arrangement of DNA and the electrostatic repulsion between DNA molecules. It was also found that ssDNA junctions on the silicon surface were not very uniform, which was related to many factors, such as the inhomogeneity of the self-assembled coupling layer, the multi-step experimental operation and the pH value of the fixation solution.

Ionization detection of neutral 2,5-dihydroxy benzoic acid molecules in the matrix-assisted laser desorption/ionization plume by ultraviolet laser post-ionization: Correlation between internal energy distribution and thermal decomposition rate

We probed neutral 2,5-dihydroxy benzoic acid (DHB) crystals in the matrix-assisted laser desorption/ionization (MALDI) plume using ultraviolet (UV) laser post-ionization at 266 nm to investigate the initial MALDI process involving fast phase transitions. Mainly three ion signals, DHB+, [DHB–H2O]+ produced by the dissociative ionization of neutral DHB, and [DHB–CO2]+ formed by pyrolysis in the dense plume, were detected using time-of-flight mass spectrometry. The [DHB–H2O]+/DHB+ ratio was utilized as the fraction of highly excited neutral DHB molecules produced by photoexcitation and survived after phase explosion, and the [DHB–CO2]+/DHB+ ratio indicated the extent of pyrolysis of neutral DHB molecules in the thermally heated condensed phase before phase explosion. The two indexes showed an inverse relationship with respect to the laser delay corresponding to the position in the plume, i.e., the [DHB–H2O]+/DHB+ ratio revealed high values at the tip of the plume, whereas the [DHB–CO2]+/DHB+ ratio increased in the rear part of the plume, reflecting the molecular dynamics of solid-to-gas phase transition involving the production of most MALDI analyte ions.

Synthesis, molecular dynamics and dielectric properties of benzoic acid intercalated kaolinite

The synthesis of new clay-organic nanocomposites with potential application value is one of the research hotspots in the field of functional materials. Herein, benzoic acid intercalated kaolinite compound (K-BzCOOH, calculated as Al 2 Si 2 O 5 (OH) 4 ·(BzCOOH) 0.556 , d (001) of 1.419 nm, and 51.5% intercalation rate) was synthesized, and its preparation methods, intercalation mechanisms and dielectric properties were investigated thoroughly. The results show that K-BzCOOH must be obtained under high pressure with K-DMSO as the precursor and methanol as the solvent. The benzoic acid molecules are arranged in an inclined monolayer between kaolinite layers, and benzene ring and the center of gravity of benzoic acid molecules are close to the surface of alumina layer. Hydrogen bonds are mainly present between H(Al-sheet) and O(c=o), and between H(coo-h) and O(Si-sheet).The interfacial interaction between inorganic and organic components is -47.11 kJ/mol. Dielectric measurements show that K-BzCOOH exhibits relaxation behavior in the range of 1-10 7 Hz and 10-100°C, attributed to the limited dipole motion of benzoic acid molecules under the action of external electric field. Also, the compound has a low dielectric constant at frequencies greater than 10 6 Hz (6.9 and 8.8 at 10°C and 100°C, respectively), which can be considered as a low- k material for semiconductor industry. • K-BzCOOH (Al 2 Si 2 O 5 (OH) 4 ·(BzCOOH) 0.556 ) was first prepared. • Intercalation mechanism probed by molecular dynamics. • K-BzCOOH exhibits two dielectric relaxation processes and low dielectric constant.

Constructing a Stable and Efficient Buried Heterojunction via Halogen Bonding for Inverted Perovskite Solar Cells

AbstractThe inverted perovskite solar cell has made great progress in recent years and the quality of the heterojunction has played a key role. Here, a series of halide‐substituted benzoic acid molecules are investigated as the bridge between nickel oxide and the perovskite, constructing a stable and efficient buried heterojunction via halogen bonding. The designed molecules are anchored at the surface of NiO by the coordination between the carboxyl and hydroxyl groups. On the opposite site of the molecules, strong halogen bonding is formed by binding the undercoordinated I− at the buried surface of the perovskite, which inhibits the generation of I2 under continuous light soaking and thereby suppresses the formation of voids. Moreover, the highly directional halogen bonding is beneficial for the oriented growth of perovskite crystals, which accelerate the carrier transport. As a result, the champion device yields a power conversion efficiency (PCE) of 22.02% and the encapsulated device maintains 91.86% of the initial PCE under continuous 1‐sun illumination at 55 °C for 1000 h.

Atomic chemical environment of tungsten in coal: Implication for the evolution of the germanium coal deposits

The Wulantuga, Lincang, and similar germanium deposits are abnormally enriched in organically associated Ge and W. In this study, the Density Functional Theory (DFT) calculation is employed to investigate the structure and bonding nature of W in coal, which helps for a better knowledge of the mode of occurrence of organically bound metals and the evolution of the coal-hosted Ge deposits.Five model compounds (ethanol, phenol, catechol, acetic acid, and benzoic acid) that represent all hydroxyls in coal structure are used to simulate the formation of W-O complexes. According to the binding energies and Natural Population Analysis (NPA) charges, W is preferred to be bonded with O-exposed model compounds to form stable W-O complexes. The phenolic hydroxyls are easier to break OH bond, suggesting that the fragments of catechol and phenol are more reactive. The carbon rings in coal are capable of bonding W, but there is less chance for graphene to be the binding site.The W-O complex can be coordinately saturated if W connects with three (catechol, acetic acid, and benzoic acid) or four (phenol and ethanol) O-exposed molecules. Generally, due to stronger binding energies, W is likely to form more stable complexes with hydroxyls relative to Ge. It is noted that W is preferred to be bonded with both O in each molecule of acetic acid or benzoic acid, and the W-O complex can reach saturation with three molecules in a distorted octahedral structure at the center. In contrast, Ge is tended to be bonded with one O in each molecule, and the Ge-O complex can be saturated with four molecules in a tetrahedral structure.The deposit evolution includes two stages: (1) Formation. The peat/lignite possesses abundant hydroxyls capable of capturing Ge and W from hydrothermal solutions and meteoric waters. Germanium and W can be fixed in the coal structure by O-bridged complexes until coal rank reaching lignite/subbituminous coal. (2) Redistribution. Along with coal rank advance to bituminous coal/anthracite, oxygen as heteroatom is expelled out from coal structure, and the bonding sites for Ge and W disappear as O-containing groups (especially hydroxyls) vanish. Thus, Ge and W can be liberated from coal.

Benzoic acid derivatives: Anti-biofilm activity in Pseudomonas aeruginosa PAO1, quantum chemical calculations by DFT and molecular docking study

ABSTRACT. Quorum sensing (QS), used by many pathogenic bacteria to express virulence factors, is seen as a new and effective strategy to combat resistant bacteria. In this study, theoretical investigations were made on the structural data of molecules to support the inhibition effects of 2-amino 4-chloro benzoic acid and 4-amino 2-chloro benzoic acid molecules. Theoretical calculations were performed by using the density functional theory with the B3LYP function and aug-cc-pVDZ basis set in the gas phase of the isolated compounds in the ground state. The biological activities of the related compounds were theoretically investigated against Covid-19 protein (PDB ID: 6LU7).
 
 KEY WORDS: 2-Amino-4-chlorobenzoic acid, 4-Amino-2-chlorobenzoic acid, Quorum sensing, Molecular docking
 Bull. Chem. Soc. Ethiop. 2023, 37(1), 171-181. 
 DOI:https://dx.doi.org/10.4314/bcse.v37i1.14

Dual‐Functional, Multi‐Targeting GNNQQNY‐AIE Conjugates as Amyloid Probes and Amyloid Modulators via Amyloid Cross‐Seeding Principle

AbstractAmyloid protein aggregation is associated with many neurodegenerative diseases, including amyloid‐β (Aβ) in Alzheimer disease, human islet amyloid polypeptide (hIAPP) in type II diabetes, and human calcitonin (hCT) in medullary thyroid carcinoma. Significant efforts have been made to develop different diagnostic and prevention strategies for the early detection and intervention of these disease‐causative protein aggregates. However, conventional design wisdoms are mostly limited to the molecules with either single function (amyloid imaging or amyloid prevention) or single targeting protein (Aβ, hIAPP, or hCT). Here, a rational design strategy of an amyloid‐aggregation‐induced emission (AIE)‐active molecule is demonstrated by conjugating an amyloid fragment of GNNQQNY (G7) with an AIE fluorescent molecule of triphenylvinyl benzoic acid (namely, G7‐TBA), making G7‐TBA as multiple‐target, dual‐function, amyloid probes and amyloid modulators for detecting, monitoring, and altering amyloid aggregation of three different amyloid proteins (Aβ, hIAPP, and hCT). G7‐TBA probe shows conformationally specific binding affinities to amyloid aggregates, switching from an “off” state (low fluorescence) for amyloid monomers to an “on” state (high fluorescence) for β‐structure‐rich amyloid oligomers and fibrils in aqueous solution. Further surface immobilization of TBA probes on surface plasmon resonance surfaces allows to amplify detection sensitivity and binding affinity to amyloid aggregates formed at different aggregation stages. G7‐TBA as amyloid modulator enables acceleration of amyloid fibrillization and selectively protects cells from hIAPP‐induced toxicity. The distinct amyloid detection and modulation of G7‐TBA are essentially derived from the cross‐seeding between G7 and amyloid aggregation via β‐structure interaction, which by far exceed the binding affinity between commercial ThT and amyloid aggregates. Such design concepts of amyloid‐AIE conjugates can be further explored as multiple‐function and target probes and/or modulators for biomedical applications.

Accelerating All-Atom Simulations and Gaining Mechanistic Understanding of Biophysical Systems through State Predictive Information Bottleneck.

An effective implementation of enhanced sampling algorithms for molecular dynamics simulations requires a priori knowledge of the approximate reaction coordinate describing the relevant mechanisms in the system. In this work, we focus on the recently developed artificial intelligence-based State Predictive Information Bottleneck (SPIB) approach and demonstrate how SPIB can learn such a reaction coordinate as a deep neural network even from undersampled trajectories. We exemplify its usefulness by achieving more than 40 times acceleration in simulating two model biophysical systems through well-tempered metadynamics performed by biasing along the SPIB-learned reaction coordinate. These include left- to right-handed chirality transitions in a synthetic helical peptide (Aib)9 and permeation of a small benzoic acid molecule through a synthetic, symmetric phospholipid bilayer. In addition to significantly accelerating the dynamics and achieving back and forth movement between different metastable states, the SPIB-based reaction coordinate gives mechanistic insights into the processes driving these two important problems.

The structure and spectroscopic characterization of coordination compounds with -phenyl-N-methylnitrone in solution and in solid state

New coordination compounds of a-phenyl-N-methylnitrone with Cu2+, Mn2+, Ni2+, and UO22+ were synthesized. Complexes were studied by means of IR, NMR and UV-Vis spectroscopies. The crystal and molecular structure of uranyl complex with a-phenyl-N-methylnitrone was determined by X-ray diffraction study. The monodentate nitrone ligands are coordinated to the metal ion via oxygen atom. The coordination polyhedron of uranium is a distorted hexagonal bipyramide. It was shown that there is dynamic process in the acetone solution in the temperature range of 203–297 K. The ligand exists as a trans-isomer for both present forms of organic ligand by the NOE difference. Dimeric copper(II) benzoate was obtained via recrystallization of the copper complex with a-phenyl-N-methylnitrone from methanol solution. According to X-ray diffraction analysis, the environment of each of the copper atoms is octahedral. The coordination sphere is formed by six oxygen atoms. Three anions of benzoic acid are coordinated bidentate-bridged through oxygen atoms of the carboxyl group, while one molecule of benzoic acid is coordinated monodentatically through the carboxyl oxygen atom.

HYDROGEN BOND IN POTENTIALLY MESOGENIC MOLECULAR COMPLEXES OF 4-(PHENYLAZO)BENZOIC ACID AND 4-(PHENYLAZO)PHENOL WITH PYRIDINE DERIVATIVES

Using experimental and theoretical methods, it has been shown that hydrogen-bonded molecular complexes in two-component systems based on 4-pyridyl-4'-n-alkyloxybenzoates (n = 7, 12) with 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol (composition of 1:1) are formed. Quantum chemistry methods (DFT (B3LYP)/cc-pVTZ) were used to determine the conformational properties of 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol molecules. It has been shown that the introduction of 4-carboxy and 4-hydroxy groups into the azobenzene molecule has practically no effect on the energy characteristics of the trans-cis isomerization process. The energy, geometric, and electronic characteristics of intermolecular hydrogen bonds in the H-complexes have been estimated. The calculations showed that the H-complexes of 4-pyridyl-4-n-propyloxybenzoate with 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol differ significantly from each other in geometric structure: the complex with 4-(phenylazo)benzoic acid – rod-shaped, complex with 4-(phenylazo)phenol – angular. A comparison of the energy characteristics of H-complexes, as well as the characteristics of hydrogen bonds, showed that a stronger hydrogen bond is formed in the complex with 4-(phenylazo)benzoic acid than in the complex with 4-(phenylazo)phenol. The results of modeling dimers of molecules of 4-(phenylazo)benzoic acid, 4-(phenylazo)phenol, reproducing intermolecular interactions in crystals, and their hydrogen-bonded complexes allow to conclude that in the process of self-organization of systems with a composition of 1:1, associates of 4-(phenylazo)benzoic acid molecules, associates of 4-(phenylazo)phenol molecules will be broken and H-complexes with 4-pyridyl-4'-alkyloxybenzoates will be formed instead. Changes in the experimental IR spectra recorded for the initial components and for systems with a composition of 1:1 confirm the formation of molecular complexes. The structural units of the studied systems based on 4-pyridyl-4'-alkyloxybenzoates with 4-(phenylazo)benzoic acid and 4-(phenylazo)phenol with a composition of 1:1 can be considered supramolecules, formed by hydrogen bonding. The structure of supermolecules and the presence of their geometric anisotropy indicate their potential mesogenicity. The sample of H-complexes of 4-(phenylazo)phenol and 4-pyridyl-4'-n-dodecyloxybenzoate (composition of 1:1) was studied for the manifestation of mesomorphic properties using the method of polarization thermomicroscopy. The textures registered in a polarizing microscope allow to conclude that the H-complex has a smectic mesophase in the temperature range of 101.4–109.4 °C.

Porous Mn-doped Co3O4 nanosheets: Gas sensing performance and interfacial mechanism investigation with In situ DRIFTS

Unraveling the gas-solid interfacial sensing mechanism during gas sensing is very essential for the development of high-performance gas sensors. In this work, the Mn-doped Co3O4 porous nanosheets with 5.6 times higher response than pristine Co3O4 and short response/recovery time (55/30 s) for 100 ppm toluene gas is synthesized. More importantly, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is conducted to investigate the gas-solid interfacial sensing mechanism over 3-Mn-Co3O4. The interfacial reaction species have been monitored, such as methylbenzene, benzyl alcohol, benzaldehyde, benzoic acid, carbon monoxide, and water molecule. These species originate from the elementary and overall reactions during toluene gas sensing. The dynamic evolution of surface species could be divided into three stages of adsorption reaction, reaction balance, and desorption reaction. Furthermore, combined with the density function theory simulation calculation, the gas-solid interfacial sensing mechanism over 3-Mn-Co3O4 is proposed. Toluene molecule reacts with the surface active oxygen species resulting in the occurrence of a series of elementary reactions and the generation of intermediates. The products of overall reaction are CO2 and H2O during gas sensing. Our work implements a meaningful exploration of in situ DRIFTS in gas-sensing field and provides a distinctive view to understand the gas-soild interfacial gas-sensing mechanism.

Investigation of non-covalent complex formation between 2-(4-hydroxyphenylazo) benzoic acid and α-Cyclodextrin in solid and solution forms

Benzoic acid and its derivatives molecules have some biological properties such as antifungal and antimicrobial properties and so these molecules have been especially used in drug industry. In this study, complex formation between alpha cyclodextrin which is a good drug delivery system and 2-(4-hydroxyphenylazo) benzoic acid was performed in both aqueous environment and solid state form. 2-(4-hydroxyphenylazo) benzoic acid, alpha cyclodextrin and 2-(4-hydroxyphenylazo) benzoic acid / alpha cyclodextrin complex were characterized with UV–Vis, FT-IR, NMR, TGA and powder XRD. Experimental results are clear that alpha cyclodextrin is good carrier system for 2-(4-hydroxyphenylazo) benzoic acid molecule. In solid form, complex formation was indicated using FT-IR and powder XRD. In solution phase, it has been shown by UV–Vis and NMR that complex formation between alpha cyclodextrin and 2-(4-hydroxyphenylazo) benzoic acid molecule was successfully performed. Moreover, according to TGA results, thermal stability of alpha cyclodextrin /2-(4-hydroxyphenylazo) benzoic acid complex was increased.

Mechanistic crystal size distribution (CSD)-based modelling of continuous antisolvent crystallization of benzoic acid

Since crystallization is one of the leading separation, isolation, and purification methods, the present mechanistic work investigated its continuous approach, presenting the precipitation of the benzoic acid molecules in a plug flow crystallizer. In some crystallization experiments, seeding was used in an attempt to eliminate spontaneous nucleation phenomena to allow better control over crystal size distribution by promoting crystal growth. At the same measurement time, a systematic mathematical model, based on mass varying expressions, kinetics and particle balance equations, was applied to predict the properties of the product crystals. Benchmarking the results of validation experiment, the established physical representation sufficiently described operation, which is confirmed by comparing various experimentally and theoretically determined process and product characteristics. Since liquid static mixers were used, a nearly perfect defined regime formation was achieved, which could be demonstrated by comparing simulated, calculated and experimentally-determined differential functional size distribution; therefore, a developed general morphology independent modelling could be built to optimise unit satisfactorily. Although crystallization of benzoic acid was investigated, the methodology can be easily applied to crystallization of other active pharmaceutical ingredients. The utilization of process analytical technologies and simulations can aid optimisation, intensification and automation, which can improve the quality of formulations.