Conformation Of Molecule Research Articles

Rigid and planar π-conjugated molecules leading to long-lived intramolecular charge-transfer states exhibiting thermally activated delayed fluorescence

Intramolecular charge transfer (ICT) occurs when photoexcitation causes electron transfer from an electron donor to an electron acceptor within the same molecule and is usually stabilized by decoupling of the donor and acceptor through an orthogonal twist between them. Thermally activated delayed fluorescence (TADF) exploits such twisted ICT states to harvest triplet excitons in OLEDs. However, the highly twisted conformation of TADF molecules results in limited device lifetimes. Rigid molecules offer increased stability, yet their typical planarity and π-conjugated structures impedes ICT. Herein, we achieve dispersion-free triplet harvesting using fused indolocarbazole-phthalimide molecules that have remarkably stable co-planar ICT states, yielding blue/green-TADF with good photoluminescence quantum yield and small singlet-triplet energy gap < 50 meV. ICT formation is dictated by the bonding connectivity and excited-state conjugation breaking between the donor and acceptor fragments, that stabilises the planar ICT excited state, revealing a new criterion for designing efficient TADF materials.

Exploring the structural heterogeneity of IgG1s: A comprehensive analysis of glycosylated and deglycosylated forms using TIMS-TOF-MS technique

Denaturation of IgG is a complex and multistep process that involves various structural changes in the protein as it loses its native conformation. IgG denaturation is crucial in therapeutic antibody development, manufacturing, and storage. Glycosylated IgG is generally more resistant to denaturing conditions due to the stabilizing effect of its glycans. In contrast, deglycosylated IgG is more vulnerable to structural disruption. In this study, we examined the intact level and large fragments of IgG glycoforms. Our investigation focused on changes in structural heterogeneity through glycosylation under denaturing conditions. Collision cross-sections (CCS) of intact level and large fragments of IgG1 molecules have been determined using reversed phase-high performance liquid chromatography-electrospray ionization-trapped ion mobility-time-of-flight mass spectrometry (RP-HPLC-ESI-TIMS-TOF-MS) technique. At the intact level, deglycosylated bevacizumab (IgG1B) and trastuzumab (IgG1T) could be differentiated at specific charge states and CCS ranges. The deglycosylated IgG1B molecule showed a broader CCS range than the IgG1T molecule. This result demonstrated that the deglycosylated IgG1T was altered from deglycosylated IgG1B in the gas phase under denaturing conditions. The lowering in the collision cross-section distribution (CCSD) values indicates a decrease in the structural heterogeneity of the intact IgG after deglycosylation. The ion mobility-mass spectrometry (IM-MS) analyses performed in this study showed that the glycans on the Fc region of IgG1s can trigger structural changes in the molecule under denaturing conditions. Depending on whether they are glycosylated or deglycosylated, various conformations of IgG1 molecules could be distinguished in RP-HPLC-TIMS-TOF-MS analysis.

Selection of the optimal formulation of the biopolymer system for the stimulation of productive formations

The object of study in this paper is the biopolymer system «X» – a complex composition that includes a biopolymer, salts and a thermal stabiliser intended for use in drilling fluids at high temperatures. The components of the formulation include complex reagent «X» for regulating structural, mechanical, rheological and filtration properties, as well as inhibitors (sodium and potassium chloride) and filler. Components of the biopolymer system (sodium chloride, organo-mineral colmatant thermal stabiliser) increase its thermal stability. One of the most problematic areas is the mechanism of sodium chloride's thermal stabilising effect. It is associated with an increase in the overall mineralisation of the drilling mud, which leads to a certain conformation of biopolymer molecules, accelerates gelation processes and counteracts the temperature dilution of the system. The results obtained can be explained as follows: – an increase in the concentration of sodium chloride leads to an increase in the ionic strength of the solution, which contributes to a change in the conformation of biopolymer molecules, enhancing intermolecular interactions and, as a result, increasing the viscosity and stability of the system; – the organo-mineral colmatant heat stabiliser promotes the formation of a filtration crust on the well walls, which prevents fluid loss and reduces rock permeability; – all components of the system interact with each other, affecting the properties of the solution. The optimum ratio of components allows achieving the required rheological characteristics and ensuring the stability of the system at high temperatures. As a result of processing the information on technologies for tapping productive horizons, the disadvantages and advantages of each of them were noted. The existing drilling fluid systems used to tap productive horizons at high temperatures were considered. However, more attention was paid to the selection of a new optimal formulation of the biopolymer system, in accordance with the specified rheological and structural and mechanical properties for further implementation in practice. This ensures the possibility of obtaining predictive parameters of the drilling mud. The proposed system has a number of advantages over similar ones, namely: – the system retains its properties at high temperatures; – the system provides the required values of viscosity, filtration and static shear stress; – due to the use of an optimal formulation, high efficiency is achieved at a relatively low cost.

Effect of the Chemical Composition and Geometry of Nanotubes on the Structure and Internal Rotation Barrier of Encapsulated Ammonia‐Boron Trifluoride: A Theoretical Investigation

AbstractThe study of the structure and conformational properties of ammonia–boron trifluoride in the cavity of 24 carbon and inorganic nanotubes using the PBE/3ζ DFT approximation showed that the conformational preference of the encapsulated molecule is determined by geometry and chemical composition of the host nanostructure. The combined effect of these factors leads to the predominance of eclipsed conformation of guest molecule for four endoclusters. In other cases, the main minimum on the potential energy surface corresponds to the staggered or pseudo‐staggered forms of BF3←NH3. The guest molecule carries the electric charge and has a shortened B←N bond. These conclusions are confirmed by the results of the virtual reaction of ammonia and boron trifluoride in the cavity of individual nanotubes.

Conformational Modulation of Efficient Macrocyclic Emitters Featuring Delayed Fluorescence by Conjugation Length and Cavity Dimensions.

The π-conjugated macrocyclic emitters with thermally activated delayed fluorescence (TADF) characteristics have attracted widespread attention in the field of organic electroluminescence (EL) materials due to their unique geometries and excellent luminescence performance. Despite the significant impact of conjugation length and cavity dimensions on molecular conformation, the influence of these factors on the excited-state properties remains understudied. Herein, we formulated a strategy aimed at modulating the conformation of TADF macrocyclic molecules containing aniline as the donor (D) unit, and triazine as the acceptor (A), linked in D-A and D-π-A alternative macrocyclic construction (MC-TNT and MC-TST). Corroborated by experimental and theoretical analyses, the compact and conformationally twisted MC-TNT exhibits efficient blue luminescence in crystalline state, facilitating EL at high doping concentrations with maximum external quantum efficiency (EQEmax) of 13.9%, leading the field of blue macrocyclic emitters. Notably, MC-TST with π-bridge and flat conformation, demonstrates diminished Coulombic repulsion, achieving nearly 100% photoluminescence quantum yield and superior horizontal dipole orientation of 85% in 5 wt% doped films, and the corresponding device's EQEmax reaches record-high 32.7% within the TADF macrocyclic domain.

Conformational Modulation of Efficient Macrocyclic Emitters Featuring Delayed Fluorescence by Conjugation Length and Cavity Dimensions

The π‐conjugated macrocyclic emitters with thermally activated delayed fluorescence (TADF) characteristics have attracted widespread attention in the field of organic electroluminescence (EL) materials due to their unique geometries and excellent luminescence performance. Despite the significant impact of conjugation length and cavity dimensions on molecular conformation, the influence of these factors on the excited‐state properties remains understudied. Herein, we formulated a strategy aimed at modulating the conformation of TADF macrocyclic molecules containing aniline as the donor (D) unit, and triazine as the acceptor (A), linked in D‐A and D‐π‐A alternative macrocyclic construction (MC‐TNT and MC‐TST). Corroborated by experimental and theoretical analyses, the compact and conformationally twisted MC‐TNT exhibits efficient blue luminescence in crystalline state, facilitating EL at high doping concentrations with maximum external quantum efficiency (EQEmax) of 13.9%, leading the field of blue macrocyclic emitters. Notably, MC‐TST with π‐bridge and flat conformation, demonstrates diminished Coulombic repulsion, achieving nearly 100% photoluminescence quantum yield and superior horizontal dipole orientation of 85% in 5 wt% doped films, and the corresponding device's EQEmax reaches record‐high 32.7% within the TADF macrocyclic domain.

High-Throughput Computational Study and Machine Learning Prediction of Electronic Properties in Transition Metal Dichalcogenide/Two-Dimensional Layered Halide Perovskite Heterostructures.

Heterostructures formed by transition metal dichalcogenides (TMDs) and two-dimensional layered halide perovskites (2D-LHPs) have attracted significant attention due to their unique optoelectronic properties. However, theoretical studies face challenges due to the large number of atoms and the need for lattice matching. With the discovery of more 2D-LHPs, there is an urgent need for methods to rapidly predict and screen TMDs/2D-LHPs heterostructures. This study employs first-principles calculations to perform high-throughput computations on 602 TMDs/2D-LHPs heterostructures. Results show that different combinations exhibit diverse band alignments, with MoS2 and WS2 more likely to form type-II heterostructures with 2D-LHPs. The highest photoelectric conversion efficiency of type-II structures reaches 23.26%, demonstrating potential applications in solar cells. Notably, some MoS2/2D-LHPs form type-S structures, showing promise in photocatalysis. Furthermore, we found that TMDs can significantly affect the conformation of organic molecules in 2D-LHPs, thus modulating the electronic properties of the heterostructures. To overcome computational cost limitations, we constructed a crystal graph convolutional neural network model based on the calculated data to predict the electronic properties of TMDs/2D-LHPs heterostructures. Using this model, we predicted the bandgaps and band alignment types of 9,360 TMDs/2D-LHPs heterostructures, providing a comprehensive theoretical reference for research in this field.

A computational method for the component screening of carrier-free nanodrugs: exemplified by berberine

The emergence of carrier-free nanodrugs as a promising drug delivery system is a significant development in the field of pharmaceutical research. The research on molecules that can form carrier-free nanodrugs can facilitate the expansion of their applications. The capacity of molecules to self-assemble with other molecules is the foundation upon which their formation of carrier-free nanodrugs is based. In this paper, we present a computational method for evaluating the assembly ability of molecules in aqueous environments. The method begins with screening the optimal conformation of a single molecule in water, then simulates the assembly behavior of two molecules in water, and finally calculates the optimal conformation of dimer in water. In comparison to the original computational method, this method describes the effect of water on molecular assembly behavior with the greatest possible realism by utilizing high-precision water environments in each step. The accuracy of the method has been validated by classical experiments, while its rationality has been demonstrated by electronic structure calculations of single molecules and assemblies. Furthermore, we employ the method to investigate the assembly capabilities of 54 molecules in the presence of berberine. The results demonstrate that anthraquinone and flavonoid molecules readily form robustly bound assemblies with berberine. This method offers a relatively efficient approach to compositional screening of carrier-free nanodrugs, thereby contributing to the advancement of the field.

Expanding Automated Multiconformer Ligand Modeling to Macrocycles and Fragments.

Small molecule ligands exhibit a diverse range of conformations in solution. Upon binding to a target protein, this conformational diversity is generally reduced. However, ligands can retain some degree of conformational flexibility even when bound to a receptor. In the Protein Data Bank (PDB), a small number of ligands have been modeled with distinct alternative conformations that are supported by X-ray crystallography density maps. However, the vast majority of structural models are fit to a single ligand conformation, potentially ignoring the underlying conformational heterogeneity present in the sample. We previously developed qFit-ligand to sample diverse ligand conformations and to select a parsimonious ensemble consistent with the density. While this approach indicated that many ligands populate alternative conformations, limitations in our sampling procedures often resulted in non-physical conformations and could not model complex ligands like macrocycles. Here, we introduce several improvements to qFit-ligand, including the use of routines within RDKit for stochastic conformational sampling. This new sampling method greatly enriches low energy conformations of small molecules and macrocycles. We further extended qFit-ligand to identify alternative conformations in PanDDA-modified density maps from high throughput X-ray fragment screening experiments. The new version of qFit-ligand improves fit to electron density and reduces torsional strain relative to deposited single conformer models and our previous version of qFit-ligand. These advances enhance the analysis of residual conformational heterogeneity present in ligand-bound structures, which can provide important insights for the rational design of therapeutic agents.

Hydrodynamic Properties and LCST Behavior of Six-Armed Star-Shaped Polymers with Arms of a Diblock Copolymer of Poly-2-Ethyl-2-Oxazine and Poly-2-Isopropyl-2-Oxazine

Star-shaped six-arm polymers with arms of the block copolymers of poly-2-ethyl-2-oxazine and poly-2-isopropyl-2-oxazine were synthesized. The branching center was hexaase[26]cyclophane. The prepared samples differed in the order of block attachment to the core. Molar masses of the two samples were 14200 and 21500 g⋅mol−1. The fractions of poly-2-ethyl-2-oxazine monomers in the arms were 61 and 65%, respectively. It was shown that the arms were strongly folded. Water-salt solutions of the star-shaped block copolymers exhibited thermoresponsiveness. The difference in the phase separation temperatures for the studied samples was caused by the differences in their molar masses and the different contents of poly-2-ethyl- and poly-2-isopropyl-2-oxazine blocks. The concentration dependences of the phase separation temperatures for the synthesized star-shaped copolymers coincided with those for the arms, despite the fact that the molecular masses of the stars and their arms differed by factor of near 6. The addition of NaCl to the aqueous of solutions of the star copolymers did not lead to significant changes in their characteristics. No influence of the order of the block attachment to the core on the molecule conformation and on the thermoresponsive behavior was found.

EC-Conf: A ultra-fast diffusion model for molecular conformation generation with equivariant consistency

Despite recent advancement in 3D molecule conformation generation driven by diffusion models, its high computational cost in iterative diffusion/denoising process limits its application. Here, an equivariant consistency model (EC-Conf) was proposed as a fast diffusion method for low-energy conformation generation. In EC-Conf, a modified SE (3)-equivariant transformer model was directly used to encode the Cartesian molecular conformations and a highly efficient consistency diffusion process was carried out to generate molecular conformations. It was demonstrated that, with only one sampling step, it can already achieve comparable quality to other diffusion-based models running with thousands denoising steps. Its performance can be further improved with a few more sampling iterations. The performance of EC-Conf is evaluated on both GEOM-QM9 and GEOM-Drugs sets. Our results demonstrate that the efficiency of EC-Conf for learning the distribution of low energy molecular conformation is at least two magnitudes higher than current SOTA diffusion models and could potentially become a useful tool for conformation generation and sampling.Scientific ContributionsIn this work, we proposed an equivariant consistency model that significantly improves the efficiency of conformation generation in diffusion-based models while maintaining high structural quality. This method serves as a general framework and can be further extended to more complex structure generation and prediction tasks, including those involving proteins, in future steps.

Symmetry properties, tunneling splittings of some vibrational energy levels and torsional IR spectra of the trans – and cis – conformers of hydroquinone molecule

Torsional vibrational states of trans − and cis − conformers belonging to point symmetry groups C2H and C2V, respectively, of hydroquinone molecules are classified according to the irreducible representations of the molecular symmetry group D2H(M). A correspondence has been established between the symmetry elements of the D2H(M) group and the symmetry elements on the torsional coordinate plane for two-dimensional surfaces of potential energy, wave functions, kinetic coefficients and dipole moment projections. A correspondence has been established between the symmetry species of the point symmetry groups C2H, C2V and the symmetry species of the molecular symmetry group D2H(M). Conformational states, barriers to internal rotation and the above-mentioned characteristics of the hydroquinone molecule were calculated at the MP2/Aug-cc-pVDZ, MP2/Aug-cc-pVQZ, MP2/Aug-cc-pVTZ, MP2/CBS(aD,aT,aQ), and CCSD(T)/dAug-cc-pVDZ levels of theory. The calculated data sets were approximated using symmetry-adapted sets of basis functions. Using a numerical solution of the vibrational Schrödinger equation of restricted dimensionality, the energies and wave functions of 50 stationary torsional states of the hydroquinone molecule were determined for the first time. The values of tunneling splittings of the ground vibrational and a number of excited torsional states of trans − and cis − conformers were determined. In particular, when calculating at the MP2/CBS(aD,aT,aQ) level of theory, the values of tunneling splittings of the ground vibrational states of trans − and cis − conformers turned were 1.32*10-6 and 1.62*10-6 cm−1, which is consistent with the experimentally established upper limit for this value in the cis − conformer by authors of [W. Caminati, S. Melandri, L. B. Favero, J.Chem.Phys., 100 (1994) 8569 – 8572] (0.2 MHz or 6.67*10-6 cm−1). The calculations of the matrix elements of the dipole moment operator and the partition function made it possible to simulate the torsional IR spectra of the molecule’s conformers at different temperatures. The frequencies of fundamental torsional vibrations in the trans – (267.1 and 269.0 cm−1) and cis – (269.5 and 270.9 cm−1) conformers, calculated at the MP2/CBS(aD,aT,aQ) level of theory, are in good agreement with the experimental value of frequency of this vibration (266 cm−1), established in [W.G. Fateley, G.L. Carlson, F.F. Bentley, J.Phys.Chem., 79 (1975) 199–204.].

SPATIAL STRUCTURE OF THE HEPTAPEPTIDE ANALOGUE OF NOCICEPTIN MOLECULE

&lt;p&gt;It is known that nociceptins are a new type of regulatory peptide. Knowledge of these peptide molecules' structural and functional properties is of great practical importance for medicine and pharmacology. Their mechanisms of action are considered anti-opioid. This scientific work is devoted to studying the spatial structure of the heptapeptide H-Phe1-Gly2-Gly3-Phe4-Val5-Gly6-Pro7-OH. It examines the conformational capabilities of this heptapeptide molecule. This neuropeptide molecule is a stable analog of the nociceptin. The biologically active conformation of the peptide molecule, which is realized upon interaction with the receptor, is included in the set of low-energy structures. Therefore, studying the spatial structure of peptide molecules is of great interest. Theoretical conformational analysis about nonvalent, electrostatic, and torsional interactions, the energy of the hydrogen bonds, and a special computer program carried out the calculations. The 10 low-energy conformations of this molecule and the values of the dihedral angles of the main chain and side chains are found, and the energy of the intra- and inter-residue interactions is estimated. It is revealed that low energy conformations of this molecule have the half-folded and folded type of backbone. The side chains of the Phe1 and Phe4 amino acids in low-energy conformations carry out effective interactions and are conformationally labile amino acids; they bring together the regions of the main chain and the side chains of the amino acids included in the heptapeptide. These folded forms bring parts of the backbone and the amino acids' side chains together, resulting in important interactions.&lt;/p&gt;

Quamtum Mechanical Study on Structural and Electronic Properties of Tert-Butyl Based Bridged Dithiophene Oxide Derivatives

Computational modeling is vital to designing and creating organic semiconductors used in solar cells, organic field-effect transistors, and other areas. This work studied the structural and electronic features of a group of substituted tert-butyl bridged dithiophene oxide derivatives using Density Functional Theory (DFT) calculations. Geometry improvements were carried out using the B3LYP hybrid functional and the 6-31G(d,p) basis set in Gaussian 09. Molecular shapes, bond lengths, bond angles, and dihedral angles were studied to find out how substitution patterns change the packing and conformation of molecules. Energy levels, distribution, and makeup of frontier molecular orbitals were found. This calculation also included finding other electronic qualities, such as electronic charges, dipole moments, and polarizabilities. Findings show that tert-butyl substitution makes the molecular backbone stiffer and limits its ability to twist compared to similar molecules that have not been replaced. The chemical geometry stays mostly the same when electron-withdrawing or electron-donating substituents are added to the tert- butyl groups. Nevertheless, the strength and location of substituents have a significant impact on frontier orbital energies. The HOMO-LUMO gap grew significantly when the nitro or cyano groups firmly pulled electrons away from derivatives. For successful charge transport, electron density plots show that the HOMO and LUMO are mainly located on the thiophene and substituent moieties, respectively. Molecular dipole moments are also strongly affected by the electronic features of substituents. This research shows how to change the optoelectronic properties of tert-butyl-based dithiophene oxide derivatives and how their structure-property relationships can be improved. The results help makes new organic semiconductors that work better in various electronic and optoelectronic uses.

КОНФОРМАЦИОННЫЕ СВОЙСТВА И ЭЛЕКТРОННАЯ СТРУКТУРА ПРОТИВООПУХОЛЕВОГО АГЕНТА TYR-SER-LEU

Molecular modeling methods were used to study the features of the spatial and electronic structure of the antitumor tripeptide YSL (Tyr-Ser-Leu), developed by Chinese scientists. The conformational analysis of the molecule revealed a limited set of its energetically preferable conformational states in a certain range of relative energy. The nature of the forces stabilizing the low-energy conformations of the tripeptide molecule was determined. As a result of the study, the energetically preferable ranges of dihedral angles, the energy contributions of interresidual interactions and hydrogen bonds, as well as the mutual arrangement of residues and their side chains in low-energy conformations of the tripeptide were also determined. Using the methods of molecular mechanics, the energy contributions of intramolecular interactions in low-energy conformational states of the molecule were obtained. Based on quantum-chemical calculations, the distribution of electron density and the values of dipole moments of the most optimal spatial structures of the YSL tripeptide molecule were determined. The reactivity of the tripeptide was also studied by quantum chemical calculations based on the obtained electronic characteristics of each low-energy conformation of the molecule. Using the calculated coordinates of the atoms of the energetically preferable structures of the molecule, their molecular models were built, the comparison of which makes it possible to identify the structural criteria necessary to create a drug suitable for clinical use.

СТРУКТУРНАЯ ОРГАНИЗАЦИЯ МОЛЕКУЛ СОЙМОРФИНОВ

The conformational capabilities of soymorphine-5 (Thr1-Pro2-Phe3-Val4-Val5-NH2), soymorphine-6 (Tyr1-Pro2-Phe3-Val4-Val5-Asn6-NH2) and soymorphine-7 (Tyr1- Pro2-Tyr3-Val4-Val5-Asn6-Ala7-NH2) molecules have been studied by the method of theoretical conformational analysis. The potential function of the system is chosen as the sum of non-valence, electrostatic and torsion interactions and the energy of hydrogen bonds. The low-energy conformations of soymorphine-5, soymorphine-6 and soymorphine-7 molecules were found, the dihedral angles of the main and side chains of amino acid residues that make up the molecule were found, and the energy of intra- and interresidual interactions was estimated. Thus, the spatial structure of soymorphine-5, soymorphine-6 and soymorphine-7 molecules can be represented by eight structural types. It can be assumed that the molecules perform their physiological functions in these structures. Comparison of the low-energy structures of soymorphins shows that in all molecules the first four low-energy conformations are representatives of the structural types efef, efee, efff, effe for soymorphine-5, effff, efeff, efffe, effee for soymorphine-6, efffff, efeffe, efffef, effeee for soymorphine-6. soymorphine-7. On the basis of these structures, it is possible to propose their artificial analogues for synthesis. It was shown that the spatial structure of soymorphine-5, soymorphine-6 and soymorphine-7 molecules is represented by the conformations of eight shapes of the peptide skeleton. The results obtained can be used to elucidate the structural and structural-functional organization of soymorphine molecules.

Conformation inversion of succinonitrile towards long-life solid-state lithium metal batteries

Solid-state lithium metal batteries are considered as the next-generation energy storage devices, but their application is significantly hindered by poor interfacial compatibility between Li anodes and solid-state electrolytes, especially for succinonitrile (SN) based electrolyte. Herein, this issue is addressed by a conformation inversion strategy via introducing a PE separator grafted with poly-(lithium 2-acrylamido-2-methylpropanesulfonic acid) (PAMPSLi) brushes into a SN-based electrolyte. The PAMPSLi brushes inverse the conformation of SN molecules through the multiple interactions between −SO3Li and cyanide groups, alleviating the corrosion reactions of SN on Li anodes. Significantly, the PAMPSLi brushes regulate Li+ transport pathway with the inversed SN molecules at the anode/electrolyte interface to achieve uniform Li deposition. Notably, the PAMPSLi brushes contribute to a solid electrolyte interphase (SEI) film rich in LiF and Li3N. Consequently, the solid-state Li||LiFePO4 batteries with the resulting electrolyte exhibit a specific discharge capacity of 115.0 mAh/g and a considerably long cycle life of 1500 cycles at 3 C. A pouch cell with a high-loading LiFePO4 cathode (18 mg cm−2) also exhibits a high areal capacity and superior safety. This study provides a novel strategy for achieving a stable electrolyte/anode interface in SN-based electrolytes, which facilitates the practical application of solid-state batteries with long life and high energy density.

Co/C Nanocomposites with Tunable Condensed States Induced by Conformation-Mediated Strategy for Electromagnetic Wave Absorption.

The strategic regulation of condensed state structures in multicomponent nanomaterials has emerged as an effective approach for achieving controllable electromagnetic (EM) properties. Herein, a novel conformation-mediated strategy is proposed to manipulate the condensed states of Co and C, as well as their interaction. The conformation of polyvinylpyrrolidone molecules is adjusted using a gradient methanol/water ratio, whereby the coordination dynamic equilibrium effectively governs the deposition of metal-organic framework precursors. This process ultimately influences the combined impact of derived Co and C in the resulting Co/C nanocomposites post-pyrolysis. The experimental results show that the condensed state structure of Co/C nanocomposites transitions from agglomerate state → to biphasic compact state → to loose packing state. Benefiting from the tunable collaboration between interfacial polarization and defects polarization, and the appropriate electrical conductivity, the diphasic compact state of Co/C nanocomposites achieves an effective absorbing bandwidth of 7.12GHz (2.1mm) and minimum reflection loss of -32.8dB. This study highlights the significance of condensed state manipulation in comprehensively regulating the EM wave absorption characteristics of carbon-based magnetic metal nanocomposites, encompassing factors such as conductivity loss, magnetic loss, defect polarization, and interface polarization.

GMP affected assembly behaviors of phosphatidylethanolamine monolayers elucidated by multi-resolved SFG-VS and BAM

The interaction between nucleotide molecules and lipid molecules plays important roles in cell activities, but the molecular mechanism is very elusive. In the present study, a small but noticeable interaction between the negatively charged phosphatidylethanolamine (PE) and Guanosine monophosphate (GMP) molecules was observed from the PE monolayer at the air/water interface. As shown by the sum frequency generation (SFG) spectra and Pi-A isotherm of the PE monolayer, the interaction between the PE and GMP molecules imposes very small changes to the PE molecules. However, the Brewster angle microscopy (BAM) technique revealed that the assembly conformations of PE molecules are significantly changed by the adsorption of GMP molecules. By comparing the SFG spectra of PE monolayers after the adsorption of GMP, guanosine and guanine, it is also shown that the hydrogen bonding effect plays an important role in the nucleotide-PE interactions. These results provide fundamental insight into the structure changes during the nucleotide-lipid interaction, which may shed light on the molecular mechanism of viral infection, DNA drug delivery, and cell membrane curvature control in the brain or neurons.

Controlling Chirogenic Effects in Porphyrin Based Supramolecular Systems: Theoretical Analysis Versus Experimental Observations.

Electronic circular dichroism (ECD) spectroscopy is a widely employed method for studying chiral analysis, requiring the presence of a chromophore close to a chiral centre. Porphyrinoids are found to be one of the best chromophoric systems serving for this purpose and enabling the application of ECD spectroscopy for chirality determination across diverse classes of organic compounds. Consequently, it is crucial to understand the induction mechanisms of ECD in the porphyrin-based complexes. The present study explores systematically the influence of secondary chromophores, bonded to an achiral zinc porphyrin or to chiral guest molecules, on the B-region of ECD spectra using the time-dependent density functional theory (TD-DFT) calculations. The study analyses the impact of change in both the conformation of achiral porphyrin (host) and change in position and conformation of chiral organic molecule (guest) on the B-band of ECD spectra (energy, intensity, sign of Cotton effect). Finally, conclusions made on model complexes are applied to published experimental data, contributing to a deeper understanding of various factors influencing ECD spectra in chiral systems. In addition, a computer program aimed to help rationalise ECD spectra by visualizing corresponding orbital energies, rotatory strengths, electric and magnetic transition moments, and angles between them, is presented.