Molecular Recognition via Hydrogen Bonding in Supramolecular Complexes: A Fourier Transform Infrared Spectroscopy Study

Highly exposed metal atomic active sites in Al2O3/CoNC: Modify reaction pathways by coupling oxygen species

The catalytic oxidation of formaldehyde (HCHO) at ambient temperature is a highly efficient, cost-effective and environmentally friendly approach for formaldehyde removal. Reactive oxygen (O*) and reactive hydroxyl groups (OH*) are the main active species in the catalytic oxidation reaction of HCHO. Therefore, it is crucial to design catalysts that can simultaneously enhance the surface concentrations of O* and OH*, thereby improving their overall catalytic performance. The present study aimed to design an Al2O3/CoNC catalyst featuring layered carbon nitride coupled with metal oxides possessing domain-limited cobalt (Co) metal active sites, to efficiently remove HCHO (≈100 %, 100 ppm, RH=50 %, GSHV=20,000 mL/(g h)) and ensure stability (more than 90 % formaldehyde removal within 450 h) at ambient temperature. The characterization revealed that the interaction between Al2O3-supported metal and CoNC resulted in enhanced confinement of Co, leading to a higher abundance of edge structures exposing more active sites. Additionally, the presence of highly dispersed Co-NX active sites and increased oxygen vacancies effectively facilitated the adsorption and activation processes of HCHO and O2, as well as the adsorption and desorption dynamics of intermediates during the reaction. These factors collectively contributed to an improved catalytic activity. The results of in situ infrared spectroscopy revealed that the catalyst improved the adsorption and activation of O2 and H2O, leading to the rapid generation of substantial amounts of O* and OH*. This synergistic interaction between Al2O3 and CoNC plays a crucial role in the sustained production of O* and OH*, promoting efficient of intermediate decomposition, and ensuring excellent catalytic activity and stability for HCHO.

Pycnoporus sanguineus Polysaccharides as Reducing Agents: Self-Assembled Composite Nanoparticles for Integrative Diabetic Wound Therapy

Purpose

Diabetic foot ulcers (DFU) are severe complications of diabetes, posing significant health and societal challenges. Elevated levels of reactive oxygen species (ROS) at the ulcer site hinder wound healing in most patients, while individuals with diabetes are also more susceptible to bacterial infections. This study aims to synthesize a comprehensive therapeutic material using polysaccharides from Pycnoporus sanguineus to promote DFU wound healing, reduce ROS levels, and minimize bacterial infections.

Methods

Polysaccharides from P.sanguineus were employed as reducing and stabilizing agents to fabricate polysaccharide-based composite particles (PCPs) utilizing silver ions as templates. PCPs were characterized via UV-Vis, TEM, FTIR, XRD, and DLS. The antioxidant, antimicrobial, and cytotoxic properties of PCPs were assessed through in vitro and cellular experiments. The effects and mechanisms of PCPs on wound healing were evaluated using a diabetic ulcer mouse model.

Results

PCPs exhibited spherical particles with an average size of 57.29±22.41 nm and effectively combined polysaccharides' antioxidant capacity with silver nanoparticles' antimicrobial function, showcasing synergistic therapeutic effects. In vitro and cellular experiments demonstrated that PCPs reduced cellular ROS levels by 54% at a concentration of 31.25 μg/mL and displayed potent antibacterial activity at 8 μg/mL. In vivo experiments revealed that PCPs enhanced the activities of superoxide dismutase (SOD) and catalase (CAT), promoting wound healing in DFUs and lowering the risk of bacterial infections.

Conclusion

The synthesized PCPs offer a novel strategy for the comprehensive treatment of DFU. By integrating antioxidant and antimicrobial functions, PCPs effectively promote wound healing and alleviate patient suffering. The present study demonstrates a new strategy for the integrated treatment of diabetic wounds and expands the way for developing and applying the polysaccharide properties of P. sanguineus.

Theoretical investigation of tube-like supramolecular structures formed through bifurcated lithium bonds

The stability of three supramolecular naostructures, which are formed through the aggregation of identical belts of [12] arene containing p-nitrophenyllithium, 1,4-dilithiatedbenzene and 1,4-dinitrobenzene units, is investigated by density functional theory. The electrostatic potential calculations indicate the ability of these belts in forming bifurcated lithium bonds (BLBs) between the Li atoms of one belt and the oxygen atoms of the NO2 groups in the other belt, which is also confirmed by deformation density maps and quantum theory of atoms in molecules (QTAIM) analysis. Topological analysis and natural bond analysis (NBO) imply to ionic character for these BLBs with binding energies up to approximately - 60 kcal mol-1. The many-body interaction energy analysis shows the strong cooperativity belongs to the configuration with the highest symmetry (C4v) containing p-nitrophenyllithium fragments as the building unit. Therefore, it seems that this configuration could be a good candidate for designing a BLB-based supramolecular nanotube with infinite size in this study.

Rotenone encapsulated in pH-responsive alginate-based microspheres reduces toxicity to zebrafish

Rotenone is a botanical pesticide and has long been used for control of insect pests and also as a natural piscicide for management of fish populations in many countries. Field application for pest control, however, often encounters the movement of rotenone into surface water due to spray drift or surface runoff after rainfall, which could potentially result in water pollution and unexpected death of fishes. To minimize its effect on freshwater and the problem of fish dying, one solution was to encapsulate rotenone in specific microspheres, limiting its release and reducing its toxicity since rotenone can be quickly degraded under sunlight. In this study, pH-responsive alginate-based microspheres were synthesized to encapsulating rotenone, which were designated as rotenone beads. The rotenone beads, along with alginate beads (devoid of rotenone) were characterized and evaluated for their responses to pH and effects on zebrafish. Results showed that the microspheres had high loading efficiency (4.41%, w/w) for rotenone, and rotenone beads well responded to solution pH levels. The cumulative release rates of rotenone from the beads were 27.91%, 42.72%, and 90.24% at pH 5.5, 7.0, and 9.0, respectively. Under acidic conditions, the rotenone release rate was lower due to hydrogen bonding. On the contrary, rotenone became more quickly released at the high pH due to intermolecular repulsion. The toxicity of rotenone beads to zebrafish and fish embryos at a pH of 5.5 was reduced by 2- and 4-fold than chemical rotenone. Since pH levels in most freshwater lakes, ponds, and streams vary from 6 to 8, rotenone release from the beads in such freshwater could be limited. Thus, the synthesized rotenone beads could be relatively safely used for pest control with limited effects on freshwater fishers.

Natural Small-Molecule-Based Carrier-Free Self-Assembly Library Originated from Traditional Chinese Herbal Medicine

The carrier-free self-assembly of small molecules opens a new window for the development of nanomaterials. This study is dedicated to developing binary small-molecular self-assemblies derived from phytochemicals in traditional Chinese herbal medicine. Among them, Rhei Radix et Rhizoma and Coptidis Rhizoma are a common pair used in clinics for thousands of years. Here, we found that there were numerous spherical supramolecular nanoparticles (NPs) originated from Rhei Radix et Rhizoma and Coptidis Rhizoma decoction. Ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) was used to analyze the composition of the supramolecules, and a total of 119 phytochemicals were identified (23 anthraquinones, 31 alkaloids, 24 organic acids, 8 tannins, and other components). Isothermal titration calorimetry (ITC) showed that the interaction between Rhei Radix et Rhizoma and Coptidis Rhizoma was a spontaneous exothermic reaction, indicating that their phytochemicals had the property of self-assembly and interacted to form supramolecules in the decocting process. Furthermore, scanning electron microscopy (SEM), UV, IR, NMR, and ITC were used to verify that rhein and coptisine could self-assemble into nanofibers (Rhe-Cop NFs), while emodin and coptisine could self-assemble into nanoparticles (Emo-Cop NPs). The formation mechanism analysis of the self-assemblies revealed that they were induced by electrostatic attraction, hydrogen bonding, and π-π stacking, forming nanospheres of about 50 nm and nanofibers. The current study not only provides an idea of discovering carrier-free self-assemblies from traditional herbal medicine decoction but also supplies a reference for the design of binary self-assembly of small molecules in the future.

Decomposition of Heavy Diesel SCR Urea Fluid Adsorbed in Cu/HZSM-5 SCR Catalysts Studied by FTIR Spectroscopy at Ambient Conditions

A method is presented to study the decomposition of urea deposited on Cu/HZSM-5 SCR catalysts and therewith the ability of the Cu/HZSM-5 SCR catalyst to be regenerated when being overdosed with SCR urea fluids during operation. This straightforward laboratory method could speed up calibration of exhaust gas aftertreatment systems. As an example, the removal of adsorbed urea to the SCR substrate due to dosage malfunction is studied. To study the removal of adsorbed urea on the catalyst substrate, FTIR experiments have been conducted to investigate the state of the catalyst. Besides Cu/HZSM-5 also HZSM-5 and CuOx were studied as model compounds to provide more inside on the processes occurring at the Cu/HZSM-5 surface upon urea decomposition. To simulate exposure of the SCR catalyst to overdosing of the urea solution, samples were impregnated with a 32 wt% urea solution, which correlates to that of commercial heavy duty diesel urea solutions. After impregnation, the samples were heated at various temperatures in the 133–400 °C temperature region, typically the operation window of a SCR catalyst. After heating, the samples were cooled to room temperature and measured in FTIR. The obtained spectra were compared with various literature reports to correlate the observed absorption bands to urea, urea related compounds and decomposition compounds. The concentration of these adsorbed species decreases at increased thermolysis temperature and is no longer visible at temperatures >250 °C. Extended heat treatment at 200 °C revealed only minor loss of adsorbents after 6 h and were still observable in the FTIR spectra after 24 h. Urea derived adsorbents were completely removed when simulating catalyst regeneration under SCR operation conditions under continuous air flow with a humidity of 10% and at elevated temperatures (400 °C).

Site-selective oral delivery of therapeutic antibodies to the inflamed colon via a folic acid-grafted organic/inorganic hybrid nanocomposite system

This study aimed to develop a pH-responsive folic acid-grafted organic/inorganic hybrid nanocomposite system for site-selective oral delivery of therapeutic antibodies. A folic acid-grafted aminoclay (FA-AC) was prepared via an in situ sol‒gel method. Then, a drug-loaded nanocomplex was prepared via the electrostatic interaction of FA-AC with infliximab (IFX), a model antibody, and coated with Eudragit® S100 (EFA-AC-IFX). FA-AC exhibited favorable profiles as a drug carrier including low cytotoxicity, good target selectivity, and capability to form a nanocomplex with negatively charged macromolecules. A pH-responsive FA-AC-based nanocomplex containing IFX (EFA-AC-IFX) was also obtained in a narrow size distribution with high entrapment efficiency (>87%). The conformational stability of IFX entrapped in EFA-AC-IFX was well maintained in the presence of proteolytic enzymes. EFA-AC-IFX exhibited pH-dependent drug release, minimizing premature drug release in gastric conditions and the upper intestine. Accordingly, oral administration of EFA-AC-IFX to colitis-induced mice was effective in alleviating the progression of ulcerative colitis, while oral IFX solution had no efficacy. These results suggest that a pH-responsive FA-AC-based nanocomposite system can be a new platform for the site-selective oral delivery of therapeutic antibodies.

Structural and mechanical properties of biodegradable poly(lactic acid) and pectin composites: using bionucleating agent to improve crystallization behavior

Biocomposites of poly(lactic acid) (PLA) and pectin, which are low-cost organic materials, were prepared using an internal mixing machine in various pectin contents, i.e., 2, 4, 6 and 8% w/w. When pectin was added as a nucleating agent, the mechanical properties of the biocomposites, such as tensile and impact testing, were considerably improved, particularly following the annealing process. In addition, the PLA–pectin annealed at 4% w/w showed the highest strength and thermal stability. This can be explained by the fact that PLA containing 4% pectin by weight had the best dispersion, as indicated by scanning electron microscopy (SEM) and synchrotron-based 2D chemical mapping FT-IR. Moreover, pectin not only serves as a reinforcing material to improve mechanical characteristics but also aids in the crystallization of PLA, which was confirmed by in situ synchrotron-based wide-angle X-ray scattering (SR-WAXS). The crystallization rate and crystallinity were maximum at 8% w/w pectin addition according to the SR-WAXS results. This shows that pectin dispersion is the most important factor in determining the mechanical and thermal properties of biocomposites.

Semi-Continuous Heterophase Polymerization to Synthesize Poly(methacrylic acid)-Based Nanocomposites for Drug Delivery

The design of nanocomposites with the potential for drug delivery is a topic of great interest. In this work, the synthesis of nanocomposites of poly(methacrylic acid) (PMAA) grafted onto carbon nanotubes (CNTs) functionalized with poly(amidoamine) (PAMAM) dendrimer by semicontinuous heterophase polymerization SHP, at three different methacrylic acid (MAA) dosing rates, is reported. SHP is a polymerization technique poorly used to prepare nanocomposites containing CNTs and has the potential to produce more ordered alkyl methacrylic polymer chains, which could favor the obtaining of a homogenous nanocomposite. For the nanocomposites synthesized, a lowest addition rate monomer-starved condition was reached. Analysis by X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) demonstrate that functionalized CNTs are grafted onto the PMAA matrix. The ability of prepared nanocomposites to deliver hydrocortisone was evaluated by ultraviolet-visible spectroscopy (UV-Vis). The hydrocortisone release profiles of pure PMAA and of their nanocomposites prepared at the lowest monomer fed rate were fitted with Higuchi and Korsmeyer–Peppas models, successfully. Functionalized CNTs have a crucial role to induce an effective release of hydrocortisone from the prepared nanocomposites.

Molecular Rationale for the Design of Instantaneous, Strain-Tolerant Polymeric Adhesive in a Stretchable Underwater Human-Machine Interface

Strain-tolerant reversible adhesion under harsh mechanical deformation is important for realizing long-lasting polymeric adhesives. Despite recent advances, cohesive failure within adhesives remains a critical problem that must be solved to achieve adhesion that is robust against humidity, heat, and mechanical stress. Here, we report a molecular rationale for designing an instantaneous polymeric adhesive with high strain tolerance (termed as iPASTE) even in a stretchable human-machine interface. The iPASTE consists of two biocompatible and eco-friendly polymers, linearly oligomerized green tea extracts, and poly(ethylene glycol) for densely assembled networks via dynamic and reversible hydrogen bonds. Other than the typical approach containing nanoclay or branched adhesive precursors, the linear configuration and conformation of such polymer chains within iPASTE lead to strong and moisture-resistant cohesion/adhesion. Based on the strain-tolerant adhesion of iPASTE, it was demonstrated that a subaqueous interactive human-machine interface integrated with a robot arm and a gold nanomembrane strain-sensitive electronic skin can precisely capture a slithery artificial fish by using finger gesture recognition.

From Critical Point to Critical Point: The Two-States Model Describes Liquid Water Self-Diffusion from 623 to 126 K

Liquid’s behaviour, when close to critical points, is of extreme importance both for fundamental research and industrial applications. A detailed knowledge of the structural–dynamical correlations in their proximity is still today a target to reach. Liquid water anomalies are ascribed to the presence of a second liquid–liquid critical point, which seems to be located in the very deep supercooled regime, even below 200 K and at pressure around 2 kbar. In this work, the thermal behaviour of the self-diffusion coefficient for liquid water is analyzed, in terms of a two-states model, for the first time in a very wide thermal region (126 K < T < 623 K), including those of the two critical points. Further, the corresponding configurational entropy and isobaric-specific heat have been evaluated within the same interval. The two liquid states correspond to high and low-density water local structures that play a primary role on water dynamical behavior over 500 K.

Preparation of alginate-chitosan floating granules loaded with 2-methyl-4-chlorophenoxy acetic acid (MCPA) and their bioactivity on water hyacinth

BACKGROUND

Water hyacinth (Eichhornia crassipes) is considered the most damaging aquatic weed in many countries. Chemical methods are still the primary approach to control, although this directly exposes the natural enemy of water hyacinth (water hyacinth weevil) to herbicides. In addition, spray drift can easily damage non-target plants. In this study, herbicides, natural polymer materials (chitosan and carboxymethyl chitosan), sodium alginate and natural oils (citronella oil) were used to prepare novel floating polysaccharide granules as a solution for controlling water hyacinth.

RESULTS

2-Methyl-4-chlorophenoxy acetic acid (MCPA) floating granules with a spherical structure were prepared using a MCPA-chitosan-sodium alginate-oil cross-linking and embedding method. The granules produced showed the required properties of floatation and slow controlled herbicide release. In addition, the polysaccharide granules collected around water hyacinth plants and enabled targeted release of the active herbicide ingredients onto the stems and roots of the weed, thereby stopping the herbicide from reaching non-target plants and preventing regrowth of water hyacinth.

CONCLUSION

We successfully prepared highly effective MCPA-loaded floating granules, which compared with an MCPA solution, exerted greater control on water hyacinth. Concomitantly, these granules provide a solution to spray drift and ensure the safety of natural enemies of water hyacinth, which is of great significance in research on herbicide formulations.

A Two Step Postsynthetic Modification Strategy: Appending Short Chain Polyamines to Zn-NH2-BDC MOF for Enhanced CO2 Adsorption

Functionalizing metal-organic frameworks (MOFs) with amines is a commonly used strategy to enhance their performance in CO₂ capture applications. As such, in this work, a two-step strategy to covalently functionalize NH₂-containing MOFs with short chain polyamines was developed. In the first step, the parent MOF, Zn₄O(NH₂-BDC)₃, was exposed to bromoacetyl bromide (BrAcBr), which readily reacts with pendant -NH₂ groups on the 2-amino-1,4-benzenedicarboxylate (NH₂-BDC^2-) ligand. ¹H NMR of the digested MOF sample revealed that as much as 90% of the MOF ligands could be functionalized in the first step. Next, the MOF samples 60% of the ligands functionalized with acetyl bromide, Zn₄O(NH₂-BDC)_1.2(BrAcNH-BDC)_1.8, was exposed to several short chain amines including ethylenediamine (ED), diethylenetriamine (DETA), and tris(2-aminoethyl)amine (TAEA). Subsequent digested ¹H NMR analysis indicated that a total of 30%, 28%, and 19% of the MOF ligands were successfully grafted to ED, DETA, and TAEA, respectively. Next, the CO₂ adsorption properties of the amine grafted MOFs were studied. The best performing material, TAEA-appended-Zn₄O(NH₂-BDC)_1.2(BrAcNH-BDC)_1.8, exhibits a zero-coverage isosteric heat of CO₂ adsorption of -62.5 kJ/mol, a value that is considerably higher than the one observed for the parent framework, -21 kJ/mol. Although the boosted CO₂ affinity only leads to a slight increase in the CO₂ adsorption capacity in the low-pressure regime (0.15 bar), which is of interest in postcombustion carbon dioxide capture, the CO₂/N₂ (15/85) selectivity at 313 K is 143, a value that is ∼35 times higher than the one observed for Zn₄O(NH₂-BDC)₃, 4.1. Such enhancements are attributed to accessible primary amines, which were grafted to the MOF ligand. This hypothesis was further supported via in situ DRIFTS measurements of TAEA-Ac-Zn₄O(NH₂-BDC)_1.2(BrAcNH-BDC)_1.8 after exposure to CO₂, which revealed the chemisorption of CO₂ via the formation of hydrogen bonded carbamates/carbamic acid and CO₂^δ- species; the latter are adducts formed between CO₂ and [amineH]⁺Br^- salts that are produced during the amine grafting step.

The explicit role of electron exchange in the hydrogen bonded molecular complexes

We applied a set of advanced bonding descriptors to establish the hidden electron density features and binding energy characteristics of intermolecular DH∙∙∙A hydrogen bonds (OH∙∙∙O, NH∙∙∙O and SH∙∙∙O) in 150 isolated and solvated molecular complexes. The exchange-correlation and Pauli potentials as well as corresponding local one-electron forces allowed us to explicitly ascertain how electron exchange defines the bonding picture in the proximity of the H-bond critical point. The electron density features of DH∙∙∙A interaction are governed by alterations in the electron localization in the H-bond region displaying itself in the exchange hole. At that, they do not depend on the variations in the exchange hole mobility. The electrostatic interaction mainly defines the energy of H-bonds of different types, whereas the strengthening/weakening of H-bonds in complexes with varying substituents depends on the barrier height of the exchange potential near the bond critical point. Energy variations between H-bonds in isolated and solvated systems are also caused the electron exchange peculiarities as follows from the corresponding potential and the interacting quantum atom analyses complemented by electron delocalization index calculations. Our approach is based on the bonding descriptors associated with the characteristics of the observable electron density and can be recommended for in-depth studies of non-covalent bonding.

The role of intermolecular interactions in stabilizing the structure of the nematic twist-bend phase

The understanding of the relationship between molecular structure and the formation of the nematic twist-bend phase is still at an early stage of development. This is mainly related to molecular geometry, while the correlation between the nematic twist-bend phase and the electronic structure is ambiguous. To explore the electronic effect on properties and stabilization of the nematic twist-bend phase we investigated 2′,3′-difluoro-4,4′′-dipentyl-p-terphenyl dimers (DTC5Cn). We used polarized fourier transform infrared spectroscopy, which can, at least in principle, provide information about the ordering in the twist-bend phase. All dimers show a significant drop in the average value of the transition dipole moment for parallel dipoles at the transition from the nematic to the twist-bend phase, and an increase for perpendicular dipoles, despite remaining unchanged for the monomer. Density functional theory calculations were used to determine the geometric and electronic properties of the hydrogen bonded complexes. We have provided experimental and theoretical evidence of stabilization of the nematic twist-bend phase by arrays of multiple hydrogen bonds (XF⋯HX, X–benzene ring).

Stabilization of the nematic twist-band phase by arrays of multiple nonspecific short-range intermolecular interactions.

Comparison of drug release behavior of bacterial cellulose loaded with ibuprofen and propranolol hydrochloride

The aim of this study was to investigate the drug release behavior from bacterial cellulose (BC). Ibuprofen and propranolol hydrochloride were used as model drugs to represent low and highly water soluble drugs. The drug was loaded into the BC by immersing the partially swollen BC in a solution of drug concentrations ranging from 0.05 to 0.5 mg mL⁻¹ and then drying by two different methods: air-drying and freeze-drying. The results showed that the type of drug and the drying method influenced the drug loading efficiency and drug release behavior. For ibuprofen, high drug loading efficiency was found when loading the drug into BC at low concentration and vice versa for propranolol hydrochloride. The drug-loaded BC prepared by the freeze-drying method showed a sustained release regardless of drug type and drug-loaded amount. The sustained release followed the Higuchi and Korsmeyer–Peppas models. On the other hand, when using the air-drying method, BC loaded with ibuprofen showed immediate release at every drug-loaded amount. However, BC loaded with propranolol hydrochloride showed immediate release at the high drug-loaded amount but showed sustained release at the low drug-loaded amount. The release of drug from a drug-loaded BC prepared by air-drying method tended to follow first-order kinetics. In conclusion, the drug loading concentration and the drying method in the drug-loaded BC preparation influenced the drug release characteristics of the BC-based drug delivery system.

The aim of this study was to investigate the drug release behavior from bacterial cellulose (BC).

Induced Phases of New H-bonded Supramolecular Liquid Crystal Complexes; Mesomorphic and Geometrical Estimation

New five rings architecture of 1:1 supramolecular hydrogen bonded (H-bonded) complexes were formed between 4-(2-(pyridin-4-yl)diazenyl-3-methylphenyl 4-alkoxybenzoates and 4-n-alkoxyphenyliminobenzoic acids. Mesomorphic and optical behaviors of three systems designed complexes were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). H-bonded interactions were confirmed via FT-IR spectroscopy. Computational calculations were carried out by density functional theory (DFT) estimation for all formed complexes. Experimental evaluations were correlated with the theoretical predictions and results revealed that, all prepared complexes possessing enantiotropic tri-mesophases with induced smectic C (SmC) and nematic temperature ranges. Moreover, DFT predicted for all formed supramolecular complexes possessing a non-linear bent geometry. Moreover, the π-π stacking of the aromatic rings plays an important role in the mesomorphic properties and thermal stabilities of observed phases. The energy changes between frontier molecular orbitals (HOMO and LUMO) and the molecular electrostatic potential (MEP) of the designed complexes were discussed and related to the experimental results.

Twist-Bend Nematogenic Supramolecular Dimers and Trimers Formed by Hydrogen Bonding

A selection of novel non-symmetric supramolecular liquid crystal dimers and trimers formed by hydrogen-bonding have been prepared and their phase behaviour characterised by polarised optical microscopy, X-ray diffraction and temperature-dependent Fourier-transform infrared spectroscopy. We mix the bent twist-bend nematogen 4-[6-(4’-cyanobiphenyl-4-yl) hexyloxy]-benzoic acid (CB6OBA) with a series of small stilbazole-based compounds 4-[(E)-2-(n-alkoxyphenyl)ethenyl]pyridines (nOS) of varying terminal chain length (n) to obtain the CB6OBA:nOS complexes. Complexes with n ≤ 7 exhibit nematic and twist-bend nematic behaviour, followed on cooling by a smectic C phase for n = 4–7, and finally, a hexatic-type smectic X phase for n = 3–7. Mixtures with n = 8–10 exhibit a smectic A phase below the conventional nematic phase, and on further cooling, a biaxial smectic Ab phase and the same hexatic-type SmX phase. Supramolecular trimers, CB6OBA:CB6OS and CB6OBA:1OB6OS, formed between CB6OBA and dimeric stilbazoles [(E)-2-(4-{[6-(4’-methoxy[1,1’-biphenyl]-4-yl)hexyl]oxy}phenyl)ethenyl]pyridine (1OB6OS) or 4-[(E)-4’-(6-{4-[(E)-2-(pyridin-4-yl)ethenyl]phenoxy}hexyl)[1,1’-biphenyl]-4- carbonitrile (CB6OS), exhibit nematic and twist-bend nematic phases, and are the first hydrogen-bonded trimers consisting of unlike donor and acceptor fragments to do so.

New chair shaped supramolecular complexes-based aryl nicotinate derivative; mesomorphic properties and DFT molecular geometry

A new series of chair-shaped liquid crystalline complexes were formed through 1 : 1 intermolecular hydrogen bonding between 4-(4-(hexyloxyphenylimino)methyl)phenyl nicotinate and 4-alkoxybenzoic acids, with different alkoxy chains.