Impact Of Intermolecular Interactions Research Articles

Experimental and Theoretical Insights into the Intermolecular Interactions in Saturated Systems of Dapsone in Conventional and Deep Eutectic Solvents.

Solubility is not only a crucial physicochemical property for laboratory practice but also provides valuable insight into the mechanism of saturated system organization, as a measure of the interplay between various intermolecular interactions. The importance of these data cannot be overstated, particularly when dealing with active pharmaceutical ingredients (APIs), such as dapsone. It is a commonly used anti-inflammatory and antimicrobial agent. However, its low solubility hampers its efficient applications. In this project, deep eutectic solvents (DESs) were used as solubilizing agents for dapsone as an alternative to traditional solvents. DESs were composed of choline chloride and one of six polyols. Additionally, water-DES mixtures were studied as a type of ternary solvents. The solubility of dapsone in these systems was determined spectrophotometrically. This study also analyzed the intermolecular interactions, not only in the studied eutectic systems, but also in a wide range of systems found in the literature, determined using the COSMO-RS framework. The intermolecular interactions were quantified as affinity values, which correspond to the Gibbs free energy of pair formation of dapsone molecules with constituents of regular solvents and choline chloride-based deep eutectic solvents. The patterns of solute-solute, solute-solvent, and solvent-solvent interactions that affect solubility were recognized using Orange data mining software (version 3.36.2). Finally, the computed affinity values were used to provide useful descriptors for machine learning purposes. The impact of intermolecular interactions on dapsone solubility in neat solvents, binary organic solvent mixtures, and deep eutectic solvents was analyzed and highlighted, underscoring the crucial role of dapsone self-association and providing valuable insights into complex solubility phenomena. Also the importance of solvent-solvent diversity was highlighted as a factor determining dapsone solubility. The Non-Linear Support Vector Regression (NuSVR) model, in conjunction with unique molecular descriptors, revealed exceptional predictive accuracy. Overall, this study underscores the potency of computed molecular characteristics and machine learning models in unraveling complex molecular interactions, thereby advancing our understanding of solubility phenomena within the scientific community.

Impact of Intermolecular Interactions between Halogenated Volatile Solid Additives and the Nonfullerene Acceptor in Organic Solar Cells

AbstractThe halogenated volatile solid additives can delicately optimize the active layer morphology of organic solar cells, improving the devices' performance, stability, and reproducibility. However, what type of intermolecular interaction occurs between the solid additives and the active layer and whether the interaction truly impacts the donor or acceptor remains debatable. Herein, the focus is on halogenated volatile solid additives with conjugated benzene rings and their influence on the morphology of the active layer composed of PM6:Y6 as they evaporated. The absorbance spectra exhibit apparent red‐shift features in Y6 absorption regions, while the donor part is unaffected. The theoretical calculation results reveal that the additives can stay between two Y6 molecules and form halogen bonds, affecting the π–π aggregation properties of Y6. As a result, the crystalline features of the active layer are altered, leading to increased charge carrier mobilities, extended charge carrier diffusion lengths, reduced bimolecular charge recombination, and thus the device performance. Especially when 1,3,5‐tri bromobenzene is used, a champion power conversion efficiency of 17.9% is attained, among the best‐performed organic solar cells comprising PM6:Y6. The findings shed light on theoretical and experimental guidelines for designing and developing volatile solid additives for highly efficient nonfullerene organic solar cells.

Tuning the crystallization and thermal properties of polyesters by introducing functional groups that induce intermolecular interactions.

The performance of sustainable polymers can be modified and enhanced by incorporating functional groups in the backbone of the polymer chain that increases intermolecular interactions, thus impacting the thermal properties of the material. However, in-depth studies on the role of intermolecular interactions on the crystallization of these polymers are still needed. This work aims to ascertain whether incorporating functional groups able to induce intermolecular interactions can be used as a suitable systematic strategy to modify the polymer thermal properties and crystallization kinetics. Thus, amide and additional ester groups have been incorporated into aliphatic polyesters (PEs). The impact of intermolecular interactions on the melting and crystallization behavior, crystallization kinetics, and crystalline structure has been determined. Functional groups that form strong intermolecular interactions increase both melting and crystallization temperatures but retard the crystallization kinetics. Selecting appropriate functional groups allows tuning the crystallinity degree, which can potentially improve the mechanical properties and degradability in semicrystalline materials. The results demonstrate that it is possible to tune the thermal transitions and the crystallization kinetics of PEs independently by varying their chemical structure.

Spin-state switching: chemical modulation and the impact of intermolecular interactions in manganese(III) complexes.

A series of mononuclear manganese(III) complexes [Mn(X-sal2-323)](ReO4) (X = 5 Cl, 1; X = 5 Br, 2; X = 3,5 Cl, 3; X = 3,5 Br, 4; and X = 5 NO2, 5), containing hexadentate ligands prepared using the condensation of N,N'-bis(3-aminopropyl)ethylenediamine and 5- or 3,5-substituted salicylaldehyde, has been synthesized. Variable temperature single-crystal X-ray diffraction, magnetic, spectroscopic, electrochemical, and spectroelectrochemical analyses, and theoretical calculations have been used to explore the role of various ligand substituents in the spin-state switching behavior of the prepared manganese(III) complexes. All five complexes consist of an analogous distorted octahedral monocationic MnN4O2 surrounding offered by the flexible hexadentate ligand and ReO4- as the counter anion. However, a disordered water molecule was detected in complex 4. Complexes 1 (X = 5 Cl) and 5 (X = 5 NO2) show gradual and complete spin-state switching between the high-spin (HS) (S = 2) and the low-spin (LS) (S = 1) state with T1/2 values of 146 and 115 K respectively, while an abrupt and complete transition at 95 K was observed for complex 2 (X = 5 Br). Alternatively, complex 3 (X = 3, 5 Cl) exhibits an incomplete and sharp transition between the HS and LS states at 104 K, while complex 4 (X = 3, 5 Br) (desolvated) remains almost LS up to 300 K and then displays gradual and incomplete SCO at a higher temperature. The nature of the spin-state switch and transition temperature suggest that the structural effect (cooperativity) plays a more significant role in comparison with the electronic effect coming from various substituents (Cl, Br, and NO2), which is further supported by the detailed structural, electrochemical, and theoretical studies.

BN-Substitution in Dithienylpyrenes Prevents Excimer Formation in Solution and in the Solid State.

Boron–nitrogen substitutions in polycyclic aromatic hydrocarbons (PAHs) have a strong impact on the optical properties of the molecules due to a significantly more heterogeneous electron distribution. However, besides these single-molecule properties, the observed optical properties of PAHs critically depend on the degree of intermolecular interactions such as π–π-stacking, dipolar interactions, or the formation of dimers in the excited state. Pyrene is the most prominent example showing the latter as it exhibits a broadened and strongly bathochromically shifted emission band at high concentrations in solution compared to the respective monomers. In the solid state, the impact of intermolecular interactions is even higher as it determines the crystal packing crucially. In this work, a thiophene-flanked BN-pyrene (BNP) was synthesized and compared with its all-carbon analogue (CCP) in solution and in the solid state by means of crystallography, NMR spectroscopy, UV–vis spectroscopy, and photoluminescence (PL) spectroscopy. In solution, PL spectroscopy revealed the solvent-dependent presence of excimers of CCP at high concentrations. In contrast, no excimers were found in BNP. Clear differences were also observed in the single-crystal packing motifs. While CCP revealed overlapped pyrene planes with centroid distances in the range of classical π-stacking interactions, the BNP scaffolds were displaced and significantly more spatially separated.

Impact of Intermolecular Interactions Between a Diketopyrrolopyrrole-Based Conjugated Polymer and Bromobenzaldehyde on Field-Effect Transistors

In this study, intermolecular interactions were investigated for increasing the charge carrier mobility of organic field-effect transistors (OFETs) based on a conjugated polymer. A diketopyrrolopyrrole (DPP)-based conjugated polymer widely used in OFETs, i.e., poly[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno[3,2-b]thiophene)] (PDPP-DTT), was assembled using 2-bromobenzaldehyde (2-BBA) and used as an active layer for OFETs. Morphological characterization and analysis for non-covalent intermolecular interactions suggested that the halogen bonding between the bromide of 2-BBA and electron-donor group of PDPP-DTT and the association between the electron-acceptor group in 2-BBA and sulfur of PDPP-DTT improved the hole transfer in the PDPP-DTT-based OFETs. The intermolecular interactions resulting from the addition of 2-BBA contributed to the two-fold enhancement of the hole mobility, two-order increase in magnitude of the current on/off ratio, and 50% decrease in the threshold voltage of the OFETs based on PDPP-DPP.

Persistent Organic Room-Temperature Phosphorescence in Cyclohexane-trans-1,2-Bisphthalimide Derivatives: The Dramatic Impact of Heterochiral vs Homochiral interactions.

Persistent metal-free room-temperature phosphorescence (RTP) materials attract significant interest owing to the production of long-lived triplet excited states. Although several organic designs show RTP, the impact of intermolecular interactions on the triplet excitons stabilization and migrations remains hardly understood because obtaining different ordered intermolecular interactions while conserving identical molecular electronic properties is very challenging. We propose here a new strategy to circumvent this problem by taking advantage of the distinct molecular packing that can be found between enantiomer and racemic forms of a chiral molecule. Structural, photophysical, and chiroptical investigations of chiral cyclohexane bisphthalimide derivatives showed that heterochiral and homochiral dimer interactions play a crucial role on the triplet excited state stabilization, resulting in higher RTP efficiency for enantiopure systems than for racemic one. This study paves the way to the use of molecular chirality to rationalize supramolecular properties arising from subtle intermolecular interactions.

Impact of intermolecular interactions on the nanofiltration of pulping liquor

Sulfite spent liquor, a side stream of the pulping process, is an abundantly available source for bio-based platform chemicals. Lignosulfonates can be separated from the other organic components and pulping chemicals by ultrafiltration. The ultrafiltration permeate can either be used directly in a fermentation process or may be further treated by nanofiltration to reduce the fermentation inhibitor concentration. FilmTec NF270 was used to study different intermolecular interactions in the ultrafiltration permeate at various pH values and lignosulfonate concentrations. Intermolecular interactions between lignosulfonates and inhibitor components decrease membrane selectivity. Several furan derivatives interact via hydrogen bonds with the hydroxyl groups of the lignosulfonates. The oxygen of the aldehyde group or the ring oxygen atom with two lone pairs were found to form hydrogen bonds and thereby affect the retention. By comparison, the hydrogen bonds of the alcohol group did not noticeably affect the retention. Magnesium as counter ion of the lignosulfonate interacts with acetate and formate ions, thereby increasing their retention. Substitution of magnesium with sodium prevents a lignosulfonate ion interaction. The investigated interactions of lignosulfonates in sulfite spent liquor may help to improve the applicability of nanofiltration processes for the detoxification of lignocellulose-derived fermentation feed. Furthermore, insights can be used for other separation methods as well because they are not specified for membrane separation processes.

Radical Stabilization Energies for Enzyme Engineering: Tackling the Substrate Scope of the Radical Enzyme QueE.

Experimental assessment of catalytic reaction mechanisms and profiles of radical enzymes can be severely challenging due to the reactive nature of the intermediates and sensitivity of cofactors such as iron-sulfur clusters. Here, we present an enzyme-directed computational methodology for the assessment of thermodynamic reaction profiles and screening for radical stabilization energies (RSEs) for the assessment of catalytic turnovers in radical enzymes. We have applied this new screening method to the radical S-adenosylmethione enzyme 7-carboxy-7-deazaguanine synthase (QueE), following a detailed molecular dynamics (MD) analysis that clarifies the role of both specific enzyme residues and bound Mg2+, Ca2+, or Na+. The MD simulations provided the basis for a statistical approach to sample different conformational outcomes. RSE calculation at the M06-2X/6-31+G* level of theory provided the most computationally cost-effective assessment of enzyme-based energies, facilitated by an initial triage using semiempirical methods. The impact of intermolecular interactions on RSE was clearly established, and application to the assessment of potential alternative substrates (focusing on radical clock type rearrangements) proposes a selection of carbon-substituted analogues that would react to afford cyclopropylcarbinyl radical intermediates as candidates for catalytic turnover by QueE.

Impact of Intermolecular Interactions, Dimeric Structures on the Glass Forming Ability of Naproxen, and a Series of Its Derivatives.

In this article, thermal properties, molecular dynamics, crystallization kinetics, and intermolecular interactions in pure naproxen (NAP), its amide (NH2-NAP), and four esters (methyl, Met-NAP; isopropyl, Iso-NAP; hexyl, Hex-NAP; and benzyl, Ben-NAP) have been investigated using differential scanning calorimetry as well as broadband dielectric and Fourier transform infrared spectroscopies. We found that the modification of the NAP molecule by substituting a hydrogen atom from the hydroxyl group strongly inhibits the crystallization tendency of this active pharmaceutical ingredient (API) and simultaneously increases its glass forming ability (GFA). In this context, it is worthwhile to stress that pure naproxen and its amide crystallized very quickly, regardless of the cooling rate. Therefore, these compounds cannot be classified as good glass-formers. On the other hand, ester derivatives of API can be easily vitrified. Moreover, dielectric measurements revealed that with an increasing molecular weight of the substituent, the rate of crystallization process slows down significantly. Consequently, Ben-NAP was characterized by the highest GFA among all investigated API esters. Comprehensive FTIR studies clearly indicated that the strong tendency to create dimeric structures in the nonmodified NAP and NH2-NAP is responsible for their enhanced crystallization. At the first sight, our results stay in contrast to most literature data, showing that H-bonds favor the glass formation ability. However, this effect is usually observed for the materials, which form extensive multidirectional hydrogen bonds and associates. In NAP and NH2-NAP, the situation is much different, since both compounds exist mainly as dimers. Therefore, one can postulate that specific intermolecular interactions are an important parameter determining the GFA of different materials, including APIs.

Photophysics of detection of explosive vapours via luminescence quenching of thin films: impact of inter-molecular interactions.

Fluorescence-based detection of explosive analytes requires an understanding of the nature of the excited state responsible for the luminescence response of a sensing material. Many measurements are carried out to elucidate the fundamental photophysical properties of an emissive material in solution. However, simple transfer of the understanding gained from the solution measurements to the solid-state can lead to errors. This is in part due to the absence of inter-molecular interactions of the chromophores in solution, which are present in the solid-state. To understand the role of inter-molecular interactions on the detection of explosive analytes we have chosen dendrimers from two different families, D1 and D2, which allow facile control of the inter-molecular interactions through the choice of dendrons and emissive chromophores. Using ultrafast transient absorption spectroscopy we find that the solution photoinduced absorption (PA) for both materials can be explained in terms of the generation of singlet excitons, which decay to the ground state, or intersystem cross (ISC) to form a triplet exciton. In neat films however, we observe different photophysical behaviours; first, ISC to the triplet state does not occur, and second, depending on the chromophore, charge transfer and charge separated states are formed. Furthermore, we find that when either dendrimer is interfaced with analyte vapour, the singlet state is strongly quenched, generating a charge transfer state that undergoes geminate recombination.

Third-order nonlinear optical properties of one-dimensional open-shell molecular aggregates composed of phenalenyl radicals.

The impact of intermolecular interactions on the third-order nonlinear optical (NLO) properties of open-shell molecular aggregates has been elucidated by considering one-dimensional aggregates of π-π stacked phenalenyl radicals with different intermolecular distances and the long-range corrected spin-unrestricted density functional theory method. In the phenalenyl dimer, which can be considered as a diradicaloid system, the diradical character strongly depends on the intermolecular distance, and the larger the intermolecular distance is, the larger the diradical character becomes. Then, around the equilibrium stacking distance that corresponds to an intermediate diradical character, its second hyperpolarizability (γ) is maximized and its value per monomer exhibits about a 30-fold enhancement with respect to the isolated phenalenyl monomer. This suggests that equilibrium is an optimal compromise between localization and delocalization of the radical electron pairs in such pancake bonding. No such effect was observed for the closed-shell coronene dimer. Moreover, when going from the dimer (diradical) to the tetramer (tetraradical), the γ-enhancement ratio increases nonlinearly with the aggregate size, whereas switching from the singlet to the highest spin (quintet) state causes a significant reduction of γ. Finally, for the tetramer, another one-order enhancement of γ is achieved for the dicationic singlet relative to its singlet neutral state. These results demonstrate the key role of intermolecular π-π stacking interactions and charge in open-shell (supra)molecular systems to achieve enhanced third-order NLO properties.

On the impact of intermolecular interactions between the quaternary ammonium ions on interlayer spacing of quat-intercalated montmorillonite: A molecular mechanics and ab-initio study

The work comprises the nature of intermolecular interactions in the organoclays modified with quaternary ammonium ions, the SOMASIF ME100 organofilized with N-octadecyltrimethylammonium ions and the commercially available Cloisite 15A. The potential energy scan was carried out for two large organoclay models with consistent-valence force field and a few others for comparison. Then, the two-body model of the interacting ions in their most and less preferable orientations was build for both systems and the more detailed, electrically neutral model of the two ions adsorbed on montmorillonite was constructed in order to investigate the non-additive interactions. The most of the work was devoted to study ab-initio calculations performed on the Unrestricted Hartree–Fock level of theory, but the electron correlation effects were also considered. The calculated interaction energy was partitioned into exchange, delocalization and electrostatic terms and the latter was distributed into its multipolar expansion. The specific intermolecular order occurring for the most and the least energetically preferred arrangements was discussed in detail with respect to the intermolecular interactions with the special emphasis on the structures underlying the occurrence of three distinctive phases in organoclay samples, for which the X-ray data was present in the literature. The basis-set dependency of the variational-perturbation scheme adopted to decompose the calculated Hartree–Fock interaction energies was examined with the use of cc-pVDZ and 6-31G basis sets. The comparison proved high reliability of the method used, even for the less extended 3-21G basis. The results revealed the presence of the relationship between the sum of two- and three-body delocalization energy terms and the inverse induced dipole moment, calculated for three body system as well as the independent functional relations between the second order electron correlation correction and Hartree–Fock delocalization and inverse Heitler–London exchange energy terms for the system of two N-octadecyltrimethylammonium cations. The equations proposed may help to predict the values of the electron correlation correction and the stabilizing delocalization energy term from the calculations at Hartree–Fock level of theory as well as from the measured module of the induced dipole moment for molecules.

Hierarchical assembly of a molecular material through the amorphous phase and the evolution of its fluorescence emission

Fabrication of an amorphous phase followed by a hierarchy of forms leading to the crystalline state offers a new dimension in the assembly of small molecule based materials. The morphology and extent of crystallinity of the nanostructures in drop-cast thin films of a diaminodicyanoquinodimethane molecule are shown to be tunable through the variation in the composition of the solvent mixture used for drop-casting. The different states of assembly starting from the solvated molecule through amorphous spherical particles, crystalline nanofibers and nano/microcrystals to bulk crystals are shown to be accompanied by a smooth variation of the fluorescence emission, the color evolving from green to blue, and the efficiency increasing steadily with the overall enhancement from the solution to the bulk crystalline state being ∼400 times. Quantum chemical computations on the molecule and its H-bonded dimer and π-dimers provide insight into the impact of intermolecular interactions in the crystalline assemblies on the electronic structure. The current study illustrates a significant departure from the conventional molecules-to-materials transition, opening up new hierarchical pathways of assembly of molecular materials.