Noncovalent Intermolecular Interactions Research Articles

Quantitative evaluation of noncovalent interactions with negative fragmentation approach including basis set superposition error correction

Abstract We propose a negative fragmentation approach (NFA), including counterpoise (CP) correction to basis set superposition error (BSSE) for quantitatively evaluating intra- and intermolecular noncovalent interactions. Noncovalent interactions are widely found in chemistry and biology and are regarded as essential interactions. However, there are few general methods for evaluating these individual intra- and intermolecular interaction energies because of two issues: (i) difficulty in the evaluation of intramolecular interactions due to the interacting sites connected with covalent bonds and (ii) BSSE affecting the quantitative accuracy of interaction analysis. In our scheme, we overcome the issue (i) using the NFA scheme, which can evaluate intra- and intermolecular interactions as a fragment–fragment interaction of interacting sites, and address the issue (ii) using the CP method. Here, NFA including the CP correction was applied to various molecular systems, providing comparable results for intermolecular interactions to supermolecule calculations with the CP correction and also succeeding in the evaluation of intramolecular interactions and its BSSEs. It is notable that our NFA scheme does not require any particular program or a modification of the program codes. These indicate that many researchers can apply our NFA scheme to various molecular systems.

Triadic Halobenzene Processing Additive Combined Advantages of Both Solvent and Solid Types for Efficient and Stable Organic Solar Cells.

Solvent additives with a high boiling point (BP) and low vapor pressure (VP) have formed a key handle for improving the performance of organic solar cells (OSCs). However, it is not always clear whether they remain in the active-layer film after deposition, which can negatively affect the reproducibility and stability of OSCs. In this study, an easily removable solvent additive (4-chloro-2-fluoroiodobenzene (CFIB)) with a low BP and high VP is introduced, behaving like volatile solid additives that can be completely removed during the device fabrication process. In-depth studies of CFIB addition into the D18-Cl donor and N3 acceptor validate its dominant non-covalent intermolecular interactions with N3 through effective electrostatic interactions. Such phenomena improve charge dynamics and kinetics by optimizing the morphology, leading to enhanced performance of D18-Cl:N3-based devices with a power conversion efficiency of 18.54%. The CFIB-treated device exhibits exceptional thermal stability (T80 lifetime = 120h) at 85°C compared with the CFIB-free device, because of its morphological robustness by evolving no residual CFIB in the film. The CFIB features a combination of advantages of solvent (easy application) and solid (high volatility) additives, demonstrating its great potential use in the commercial mass production of OSCs.

Synthesis, structural characterization, molecular docking analysis and Carbonic Anhydrase IX inhibitory evaluations of novel Cerium(III)-based MOF constructed from 1,10-phenanthroline and fumaric acid.

In this study, a novel Cerium-based MOFs with 1,10-phenanthroline (phen) and fumaric acid (H2fum) has been hydrothermally synthesized as single crystal structurally characterized by X-ray diffraction, IR spectroscopy and ATG measurements. This compound corresponds to the formula: [Ce2(phen)2(fum)3(H2O)2]n(I), it crystallizes in the triclinic system with space group P1¯, with the following parameters: a = 9.062(1) Å, b = 10.0608(5) Å, c = 10.603(1) Å, α = 72.545(6) °, β = 77.57(1) °, γ = 69.959(6) °, V = 859.49(14) Å3, Z = 2.The structure revealed 2D bridged polymeric chains where the adjacent Ce(III) atoms are bridged by fumarate linkers with a mean intermetallic distance of about 9.36 Å. H···O bonds link the 2D sheets leading to a pseudo 3D network, while the stability of the structure is assured by a weak π-π stacking between parallel and opposed phen ligands.The Ce3+ cation is nona-coordinated and it is in a distorted tricapped trigonal prism geometry.Hirshfeld surface analysis was used to investigate the non-covalent intermolecular interactions and the dominant H···O, H···C and H···H contacts were quantified. The thermal properties of the considered coordination polymer (I) are also discussed and disclose that (I) is stable up to 300°C. Besides, this study explores the potential of (I) as an inhibitor of the carbonic anhydrase IX enzyme (CA IX), a critical player in tumor microenvironment regulation. Through molecular docking simulations, we elucidate the binding interactions between (I) and CA IX, the results suggest the efficiency of (I) as a CA IX inhibitor. Moreover, we assessed the drug-likeness properties and ADMET characteristics of (I), providing valuable insights for its potential as a therapeutic agent.

A zero-dimensional 1-butylpiperazine-cadmium(II) hybrid material: Synthesis, structural analysis, and DFT studies

This study reports the synthesis and characterization of an organoammonium-cadmium(II) hybrid material, (BPH₂)₂[Cd₂Cl₈] (BP = 1-butylpiperazine), using a combination of experimental and theoretical techniques. Single-crystal X-ray diffraction shows a centrosymmetric crystal structure in the P1¯ space group, featuring a zero-dimensional (0D) arrangement where binuclear [Cd₂Cl₈]⁴⁻ anions and (C₈H₂₀N₂⁺) cations are linked by N—H···Cl and C—H···Cl hydrogen bonds. Hirshfeld surface analysis further elucidates these intermolecular noncovalent interactions, highlighting the dominant role of H···Cl contacts in the molecular packing. The crystal morphology is further investigated via the Bravais-Friedel-Donnay-Harker (BFDH) model. Infrared (IR) spectroscopic analysis was conducted to identify vibrational modes, confirm structure, and elucidate bonding features. Additionally, Experimental UV-visible study indicates an optical band gap energy of 4.75 eV, and density functional theory (DFT) calculations corroborate these findings, predicting a direct band gap of 4.45 eV. Moreover, theoretical calculations, including the complex dielectric function, band structure, and total density of states (DOS), were performed to explore the electrical and optical properties. Finally, the chemical reactivity was evaluated using conceptual-DFT descriptors at the B3LYP/SDD/aug-cc-pVTZ level of theory.

Quantification of CH and NH/π-Stacking Interactions in Cells Using Nuclear Magnetic Resonance Spectroscopy.

π-Stacking, a type of noncovalent interactions involving aromatic residues, plays an important role in protein folding and function. In this work, an attempt has been made to measure CH/π and NH/π stacking interactions in a protein in Escherichia coli cells using a combined double-mutant cycle and nuclear magnetic resonance spectroscopy method. The results show that the CH/π and NH/π stacking interactions are generally weaker in cells than those in the buffer. The transient intermolecular noncovalent interactions between the protein and the complex cellular environment may compete with and thus weaken the stacking interactions in the protein. The weakening of stacking interactions can enhance the local conformational opening of proteins in E. coli cells. This is evident from the faster rates of amide hydrogen/deuterium exchange observed in cells than in the buffer, for residues that undergo local conformational opening. This study highlights the influence of the cellular environment on π-stacking and the conformational dynamics of proteins.

Glucoconjugated Dinuclear Copper(II) Complex: An Efficient Catalyst for Stereoselective Synthesis of Trisubstituted Propargylamines via Solvent-free A3 Coupling Reaction.

Development of catalytic systems using nontoxic natural precursors is the need of the era, and along this line, we have synthesized a new D-glucose derived ligand (4,6-O-ethylidene-N-(2-hydroxy-4-(octyloxy)benzylidene)-β-D-glucopyranosylamine) and its dinuclear copper(II) complex. The molecular structure of the complex has been established by single-crystal X-ray diffraction studies and detailed noncovalent intermolecular interactions present in it has been explored by Hirshfeld surface analysis. Further, the complex has been used as catalyst in the enantioselective (87-99% ee) synthesis of propargylamines in good to excellent yield (82-95%) via aldehyde-amines-alkynes (A3) coupling reaction under solvent-free condition. The formation of aminal intermediate during the reaction has been confirmed by 1H-NMR and single-crystal X-ray diffraction studies. The catalytic system is reusable without any appreciable loss in the enantioselectivity or product yield.

Nanoparticles of nucleotide-free analogue of vitamin B12 formed in protein nanocarriers and their neuroprotective activity in vivo

Recently, we have described the first supermolecular nanoentities of vitamin B12 derivative, viz. monocyano form of heptabutyl cobyrinate, unique nanoparticles with strong noncovalent intermolecular interactions, emerging optical and catalytic properties. Their nearest analogue, heptamethyl cobyrinate (ACCby), exhibits bioactivity. Here, we demonstrate the first example of the formation of nanoparticles of this nucleotide-free analogue of vitamin B12 in protein nanocarriers and neuroprotective activity in vivo of the own nanoform of the drug. The preparation and characterization of nanocarriers based on bovine serum albumin (BSA) loaded with vitamin B12 (viz. cyano- and aquacobalamins) and ACCby were performed. Nucleotide-free analogue of vitamin B12 is tightly retained by the protein structure and exists in an incorporated state in the form of nanoparticles. The effect of encapsulated drugs on the character and severity of primary generalized seizures in rats induced by the pharmacotoxicant thiosemicarbazide was studied. Cyanocobalamin and ACCby exhibited a neuroprotective effect. The best influence of the encapsulation on the effectiveness of the drugs was achieved in the case of AСCby, whose bioavailability as a neuroprotector did not change upon introduction in BSA particles, i.e., 33 % of surviving animals were observed upon ACCby administration in free form and in encapsulated state. No surviving rats were observed without the administration of drugs. Thus, BSA nanocarriers loaded by nanoparticles of nucleotide-free analogues of vitamin B12, including hydrophobic ones, can be recommended for neuroprotection and targeted delivery.

An Energetic and Topological Approach to Understanding the Interplay of Noncovalent Interactions in a Series of Crystalline Spiropyrrolizine Compounds.

Synthesis of quinoline-containing spiropyrrolizine was achieved via a 1,3-dipolar cycloaddition reaction of azomethine ylide (generated in situ from ninhydrin and l-proline) and (E)-2-styrylquinoline. The synthesized compounds were characterized by 1H NMR, 13C NMR, HRMS, and single-crystal XRD analysis. The XRD data revealed that the solid-state structures of the compounds belong to the monoclinic system of the space group P21/c and are stabilized through various weak noncovalent interactions such as C-H···O, C-H···π, and π···π interactions. The noncovalent interactions are characterized and quantified through Hirshfeld surface analysis. Moreover, the interaction energies of the intermolecular noncovalent interactions are calculated through PIXEL calculation. The PIXEL calculation provides precise interaction energy with an energy decomposition scheme. Energy Framework calculations have also been performed to delve deeper into understanding the intermolecular interactions. The intermolecular interactions are further characterized using Bader's theory of "atoms in molecules" (QTAIM) and the "noncovalent" (NCI) interaction plot index. The nature and strength of noncovalent interactions are analyzed from the topological parameters at (3, -1) bond critical points (BCPs).

Computational Insights for interactions between NsP2 and NsP3 of CHIKV and Hormones through DFT computations and Molecular Dynamics Simulations.

The non-structural protein (nsP2 & nsP3) of the CHIKVis responsible for the transmission of viral infection. The main role of nsp is involved in the transcription process at an early stage of the infection. In this work, authors have studied the impact of nsP2 and nsP3 of CHIKV on hormones present in the human body using a computational approach. The ten hormones of chemical properties such as 4-Androsterone-2,17-dione, aldosterone, androsterone, corticosterone, cortisol, cortisone, estradiol, estrone, progesterone and testosterone were taken as a potency. From the molecular docking, the binding energy of the complexes is estimated, and cortisone was found to be the highest negative binding energy (-6.57 kcal/mol) with the nsP2 protease and corticosterone with the nsP3 protease (-6.47 kcal/mol). This is based on the interactions between hormones and NsP2/NsP3, which are types of noncovalent intermolecular interactions categorized into three types: electrostatic interactions, van der Waals interactions, and hydrogen-bonding. To validate the docking results, molecular dynamics simulations and MM-GBSA methods were performed. The change in enthalpy, entropy, and free energy were calculated using MM-GBSA methods. The nsP2 and nsP3 protease of CHIKV interact strongly with the cortisone and corticosterone with free energy changes of -20.55 & -36.08 kcal/mol, respectively.

Guanidinium and spermidinium decavanadates: as small biomimetic models to understand non-covalent interactions between decavanadate and arginine and lysine side chains in proteins

During the last three decades, numerous investigations have been conducted on polyoxidovanadates to treat several illnesses and inhibit enzymes. Numerous decavanadate compounds have been proposed as potential therapies for Diabetes mellitus, Cancer, and Alzheimer’s disease. Only six relevant functional proteins interacting with decavanadate, V10, have been deposited in the PDB. These are acid phosphatase, tyrosine kinase, two ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), the human transient receptor potential cation channel (TRPM4), and the human cell cycle protein CksHs1. The interaction sites in these proteins mainly consist of Arginine and Lysine, side chains binding to the decavanadate anion. To get further knowledge regarding non-covalent interactions of decavanadate in protein environments, guanidinium and spermidinium decavanadates were synthesized, crystallized, and subjected to analysis utilizing various techniques, including FTIR, Raman, 51V-NMR, TGA, and X-ray diffraction. The DFT calculations were employed to calculate the interaction energy between the decavanadate anion and the organic counterions. Furthermore, the Quantum Theory of Atoms in Molecules (QTAIM) and Non-covalent Interaction-Reduced Density Gradient (NCI-RDG) analyses were conducted to understand the non-covalent interactions present in these adducts. Decavanadate can engage in electrostatic forces, van der Waals, and hydrogen bond interactions with guanidinium and spermidinium, as shown by their respective interaction energies. Both compounds were highly stabilized by strong hydrogen bond interactions N−H···O and weak non-covalent interactions C−H···O. In addition, the interactions between guanidinium and spermidinium cations and decavanadate anion form several stable rings. This study provides new information on non-covalent intermolecular interactions between decavanadate and small biomimetic models of arginine and lysine lateral chains in protein environments.

A bioinspired supramolecular nanoprodrug for precision therapy of B-cell non-Hodgkin’s lymphoma

Fludarabine (FA) is still considered as a first-line chemotherapy drug for hematological tumors related to B lymphocytes. However, it is worth noting that the non-specific distribution and non-different cytotoxicity of FA may lead to irreversible consequences such as central nervous system damage such as blindness, coma, and even death. Therefore, it is very important to develop a system to targeting delivery FA. In preliminary studies, it was found that B lymphoma cells would specific highly expressing the sialic acid-binding immunoglobulin-like lectin 2 (known as CD22). Inspired by the specific recognition of sialic acid residues and CD22, we have developed a supramolecular prodrug based on polysialic acid, an endogenous biomacromolecule, achieving targeted-therapy of B-cell non-Hodgkin’s lymphoma (B-NHL). Specifically, the prepared hydrophobic reactive oxygen species-responsive FA dimeric prodrug (F2A) interacts with the TPSA, which polysialic acid were modified by the thymidine derivatives, through non-covalent intermolecular interactions similar to “Watson–Crick” base pairing, resulting in the formation of nanoscale supramolecular prodrug (F@TPSA). Cell experiments have confirmed that F@TPSA can be endocytosed by CD22+ B lymphoma cells including Raji and Ramos cells, and there is a significant difference of endocytosis in other leukocytes. Furthermore, in B-NHL mouse model, compared with FA, F@TPSA is determined to have a stronger tumor targeting and inhibitory effect. More importantly, the distribution of F@TPSA in vivo tends to be enriched in lymphoma tissue rather than nonspecific, thus reducing the leukopenia of FA. The targeted delivery system based on PSA provides a new prodrug modification strategy for targeted treatment of B-NHL.Graphical abstract

Crystalline Porous Organic Cage Membranes Constructed Using Fortified Intermolecular Interactions for Molecular Sieving.

Among the various types of materials with intrinsic porosity, porous organic cages (POCs) are distinctive as discrete molecules that possess intrinsic cavities and extrinsic channels capable of facilitating molecular sieving. However, the fabrication of POC membranes remains highly challenging due to the weak noncovalent intermolecular interactions and most reported POCs are powders. In this study, we constructed crystalline free-standing porous organic cage membranes by fortifying intermolecular interactions through the induction of intramolecular hydrogen bonds, which was confirmed by single-crystal X-ray analysis. To elucidate the driving forces behind, a series of terephthaldehyde building blocks containing different substitutions were reacted with flexible triamine under different conditions via interfacial polymerization (IP). Furthermore, density functional theory (DFT) calculations suggest that intramolecular hydrogen bonding can significantly boost the intermolecular interactions. The resulting membranes exhibited fast solvent permeance and high rejection of dyes not only in water, but also in organic solvents. In addition, the membrane demonstrated excellent performance in precise molecular sieving in organic solvents. This work opens an avenue to designing and fabricating free-standing membranes composed of porous organic materials for efficient molecular sieving.

Crystalline Porous Organic Cage Membranes Constructed Using Fortified Intermolecular Interactions for Molecular Sieving

AbstractAmong the various types of materials with intrinsic porosity, porous organic cages (POCs) are distinctive as discrete molecules that possess intrinsic cavities and extrinsic channels capable of facilitating molecular sieving. However, the fabrication of POC membranes remains highly challenging due to the weak noncovalent intermolecular interactions and most reported POCs are powders. In this study, we constructed crystalline free‐standing porous organic cage membranes by fortifying intermolecular interactions through the induction of intramolecular hydrogen bonds, which was confirmed by single‐crystal X‐ray analysis. To elucidate the driving forces behind, a series of terephthaldehyde building blocks containing different substitutions were reacted with flexible triamine under different conditions via interfacial polymerization (IP). Furthermore, density functional theory (DFT) calculations suggest that intramolecular hydrogen bonding can significantly boost the intermolecular interactions. The resulting membranes exhibited fast solvent permeance and high rejection of dyes not only in water, but also in organic solvents. In addition, the membrane demonstrated excellent performance in precise molecular sieving in organic solvents. This work opens an avenue to designing and fabricating free‐standing membranes composed of porous organic materials for efficient molecular sieving.

An Innovative Vortex-Assisted Liquid-Liquid Microextraction Approach Using Deep Eutectic Solvent: Application for the Spectrofluorometric Determination of Rhodamine B in Water, Food and Cosmetic Samples.

A new green and highly sensitive method for the determination of rhodamine B (RhB) by deep eutectic solvent-based vortex-assisted liquid-liquid microextraction with fluorescence detection (DES-VALLME-FLD) was developed. The extraction efficiency of conventional solvents and different deep eutectic solvent (DES) systems composed of tetrabutylammonium bromide (TBAB) and an alcohol (hexanol, octanol, or decanol) in different ratios were compared. DFT calculations of intermolecular electrostatic and non-covalent interactions of the most stable RhB forms with DES and water explain the experimental DESs' extraction efficiency. Semiempirical PM7 computations were used to obtain Hansen solubility parameters, which supported the good solubility of the monocationic RhB form in selected DESs. The dependence of the linear calibration of microextraction into 100 µL DES was observed in the RhB calibration range from 0.2 to 10.0 µg L-1 with a correlation coefficient of R2 = 0.9991. The LOD value was calculated to be 0.023 µg L-1. The accuracy and precision of the proposed method were verified over two days with RSD values of 2.9 to 4.1% and recovery of 94.6 to 103.7%. The developed method was applied to the determination of RhB in real samples (tap water, energy drink, and lipstick).

Mutual synergistic regulation of chloride anion and cesium cation binding using a new designed macrocyclic multi-functional sites receptor: A case of DFT computational prediction.

The mutual synergistic regulation of the multi-functional sites on a single receptor molecule for ion-binding/recognition is vital for the new receptor design and needs to be well explored from experiment and theory. In this work, a new macrocyclic ion receptor (BEBUR) with three functional zones, including two ether holes and one biurea groups, is designed expecting to mutually enhance the ion-binding performance. The binding behaviors of BEBUR mainly for Cl- and Cs+ are deeply investigated by using density functional theoretical calculations. It is found that Cl-/Cs+ binding can be mutually enhanced and synergistically regulated via corresponding conformational changes of the receptor, well reflecting an electrical complementary matching and mutual reinforcement effect. Moreover, solvent effect calculations indicate that BEBUR may be an excellent candidate structure for Cl--binding with the enhancement of counter ion (Cs+) in water and toluene. In addition, visualization of intermolecular noncovalent interaction is used for analysis on the nature of the binding interactions between receptor and ions.

A novel one-dimensional thiocyanate-bridged cobalt(III) complex: synthesis, crystal structure characterization and Hirshfeld surface analysis.

A new one-dimensional thiocyanate-bridged cobalt(III) Schiff base complex, namely, catena-poly[[[4-bromo-2-((Z)-{[2-(thiophen-2-yl)ethyl]imino}methyl)phenolato-κ2N,O]cobalt(III)]-μ-thiocyanato-κ2N:S], [Co(SCN)(C13H11BrNOS)2]n or [Co(μ1,3-SCN)L2]n (1), where HL is 4-bromo-2-((Z)-{[2-(thiophene-2-yl)ethyl]imino}methyl)phenol, a bidentate Schiff base prepared from the condensation reaction of 5-bromosalicylaldehyde and 2-(thiophen-2-yl)ethylamine, has been synthesized by stirring Co(ClO4)2·6H2O, the Schiff base HL and ammonium thiocyanate (in a 1:2:1 molar ratio) in ethanol medium. The complex was characterized by FT-IR, electronic spectra and single-crystal X-ray diffraction (SC-XRD) studies. The SC-XRD data suggest that the compound crystallizes in the orthorhombic space group Pca21. The CoIII ion in 1 adopts a distorted octahedral geometry, the metal sites being six-coordinated by one thiocyanate N atom and one thiocyanate S atom in apical positions, and by two imine N atoms and two phenolate O atoms from two anionic L- ligands which form the basal plane. The thiocyanate ligand acts as a μ-1,3 bridge, joining neighbouring CoIII atoms and forming a uniform zigzag one-dimensional polymeric chain. The crystallographic data were also used in the Hirshfeld surface (HS) analysis, which aimed to investigate the nature and quantitative significance of any noncovalent intermolecular interactions inside the crystal lattice. The crystal void parameters have also been computed and show the molecules to be tightly packed.

Synthesis of Technetium Carboxylates: Wheel-Like Octanuclear Clusters (Tc8(μ-O)8(RCOO)16, Where R = CF3, C6H5)─Potential Nanobuilding Units for Tc-MOFs.

Herein, we studied the behavior of TcO4- in trifluoroacetic anhydride (TFAA) under visible light irradiation in situ by UV-vis spectroscopy. One carboxylate of Tc(VII) C2F3O5Tc (1) and two wheel-like carboxylate clusters of Tc(IV) Tc8(μ-O)8(CF3COO)16 (2, 3) and Tc8(μ-O)8(C6H5COO)16 (4) were synthesized and analyzed using pXRD, TGA, UV-vis spectroscopy, and SCXRD techniques. According to SCXRD, it was found that Tc(IV) trifluoroacetate exists in two crystalline modifications. By UV-vis spectroscopy and DFT calculations, it was shown that the primary compound in the reaction system is trifluoroacetate Tc(VII). A technetium trifluoroacetate(VII) and Tc intermediates of unidentified nature both show photosensitivity. The influence of intermolecular noncovalent interactions on the volatility of trifluoroacetate and benzoate Tc(IV) is shown. The main regularities of chemical transformations of technetium in nonaqueous solutions of carboxylates have been revealed. The obtained data on the kinetics of the process suggest that technetium in trifluoroacetic anhydride can simultaneously exist in the form of Tc(VII), Tc(VI), Tc(V), and Tc(IV). Under laser ionization or prolonged heating, the formation of the Tc(II,III)-cluster is observed.

Self-assembly of a ruthenium-based cGAS-STING photoactivator for carrier-free cancer immunotherapy

The cGAS (cyclic GMP-AMP synthase)-STING (stimulator of interferon genes) pathway promotes antitumor immune responses by sensing cytosolic DNA fragments leaked from nucleus and mitochondria. Herein, we designed a highly charged ruthenium photosensitizer (Ru1) with a β-carboline alkaloid derivative as the ligand for photo-activating of the cGAS-STING pathway. Due to the formation of multiple non-covalent intermolecular interactions, Ru1 can self-assemble into carrier-free nanoparticles (NPs). By incorporating the triphenylphosphine substituents, Ru1 can target and photo-damage mitochondrial DNA (mtDNA) to cause the cytoplasmic DNA leakage to activate the cGAS-STING pathway. Finally, Ru1 NPs show potent antitumor effects and elicit intense immune responses in vivo. In conclusion, we report the first self-assembling mtDNA-targeted photosensitizer, which can effectively activate the cGAS-STING pathway, thus providing innovations for the design of new photo-immunotherapeutic agents.

The Role of Hydrogen Bonding in the Raman Spectral Signals of Caffeine in Aqueous Solution.

The identification and quantification of caffeine is a common need in the food and pharmaceutical industries and lately also in the field of environmental science. For that purpose, Raman spectroscopy has been used as an analytical technique, but the interpretation of the spectra requires reliable and accurate computational protocols, especially as regards the Resonance Raman (RR) variant. Herein, caffeine solutions are sampled using Molecular Dynamics simulations. Upon quantification of the strength of the non-covalent intermolecular interactions such as hydrogen bonding between caffeine and water, UV-Vis, Raman, and RR spectra are computed. The results provide general insights into the hydrogen bonding role in mediating the Raman spectral signals of caffeine in aqueous solution. Also, by analyzing the dependence of RR enhancement on the absorption spectrum of caffeine, it is proposed that the sensitivity of the RR technique could be exploited at excitation wavelengths moderately far from 266 nm, yet achieving very low detection limits in the quantification caffeine content.

Terminal group engineering of oligothiophene donors for efficient organic solar cells

All-small-molecule organic solar cells exhibit high reproducibility than polymer-based cells. Benzodithiophene and oligothiophene based derivatives are the most widely studied small molecule donors. The lower synthetic complexity and superior stability make oligothiophene based derivatives more promising for large scale production. Recently, a thiazole-centered oligothiophene donor Tz6T yields a high efficiency but deserves further improving. Substitution of halogen atoms on the end groups is proven to affect molecular packing through various non-covalent intermolecular interactions. Here we adopt terminal group engineering to regulate the optoelectronic properties of Tz6T. Through chlorine substitution, highest efficiency (9.60 %) is achieved in Tz6T-PH-Cl-4: eC9-4F binary device. Our results shed light on the structure-function relationship, and provide valuable insights into the regulation of phase separation.