Influence Of Solvent Polarity Research Articles

Influence of Solvent Polarity on the Conformer Ratio of Bicalutamide in Saturated Solutions: Insights from NOESY NMR Analysis and Quantum-Chemical Calculations

The study presents a thorough and detailed analysis of bicalutamide’s structural and conformational properties. Quantum chemical calculations were employed to explore the conformational properties of the molecule, identifying significant energy differences between conformers. Analysis revealed that hydrogen bonds stabilise the conformers, with notable variations in torsion angles. Conformers were classified into ‘closed’ and ‘open’ types based on the relative orientation of the cyclic fragments. NOE spectroscopy in different solvents (CDCl3 and DMSO-d6) was used to study the conformational preferences of the molecule. NOESY experiments provided the predominance of ‘closed’ conformers in non-polar solvents and a significant presence of ‘open’ conformers in polar solvents. The proportions of open conformers were 22.7 ± 3.7% in CDCl3 and 59.8 ± 6.2% in DMSO-d6, while closed conformers accounted for 77.3 ± 3.7% and 40.2 ± 6.2%, respectively. This comprehensive study underscores the solvent environment’s impact on its structural behaviour. The findings significantly contribute to a deeper understanding of conformational dynamics, stimulating further exploration in drug development.

Two-photon absorption in bioactive C4-substituted Coumarin derivatives: Impact of electron-withdrawing and donating groups in different environment

The versatile applications of coumarin derivatives in materials processing, fluorescence imaging, data storage, and photodynamic therapy have sparked considerable interest in scientific community. In this research paper, we explore the UV–vis spectra, IR spectra, and two photon absorption (TPA) characteristics of biological active coumarin derivatives under the influence of electron withdrawing (specifically X = CONH2, CHO, and NO2) and electron donating (X= -CH3, -OH, -NH2) functional groups at C-4 position. To delve into the absorption spectra, we employ time-dependent density functional theory calculations. Results revealed that acceptor functional groups (specifically R = CONH2, CHO, and NO2) not only lower the energy of the lowest two photon active state but also increase the corresponding TPA cross-section. Furthermore, using the Conductor-like Polarizable Continuum Model (CPCM), the influence of solvent polarity on C-4 substituted coumarin derivative was also investigated. Our findings effectively capture how substitutions and solvents impact the nonlinear optical response in coumarins, as evidenced by the measurement of the two-photon absorption cross-section (σTPA). This study offers valuable insights for identifying and designing novel coumarin derivatives with C4 substitutions, unlocking new and intriguing possibilities for their practical applications.

Adsorption of Asphaltenes at Model Oil/Brine Interface: Influence of Solvent Polarity.

With the exploitation of heavy oil worldwide, the influence of asphaltene aggregation in the oil phase on the stability of crude oil emulsion has been paid more and more attention. Under this background, the effects of solvent polarity on model oil/brine water interfacial properties and emulsion stability are investigated in this study. It is demonstrated that there is a critical asphaltene concentration for the formation of a stable emulsion. This critical concentration is then found to increase from 80 to 500 ppm with the mixing ratio of methylnaphthalene to n-decane changed from 2:3 to 7:3. The dynamic light scattering experiment shows that the average aggregate size increases abruptly from 132.8 to 261.1 nm at 2:3 mixing ratio of methylnaphthalene to n-decane once the asphaltenes are added to above the critical concentration. Accordingly, the diffusion coefficient of the asphaltenes decreases sharply from 4.36 × 10-12 to 5.68 × 10-13 m2/s. Similar conclusions are also found for the other mixing ratios of 1:1, 3:2, and 7:3. Besides, the aggregation degree of asphaltenes weakens, and the diffusion coefficient enlarges at the same asphaltene concentration with the enhancement of the solvent polarity. Further, the interfacial experiments manifest that the equilibrium interfacial dilation modulus decreases from 38.42 to 23.65 mN/m with the mixing ratio of methylnaphthalene to n-decane increased from 2:3 to 7:3. It can thus be inferred that the structural strength of the interfacial film decreases with the enhancement of the solvent polarity.

Exploring Tunable Properties, Solvent-Modulated Dynamics, and Novel C(sp3)-H Activation Mechanisms in Electron Donor-Acceptor Complexes.

Electron donor-acceptor (EDA) complex photochemistry has emerged as a vibrant area in visible-light-mediated synthetic radical chemistry. However, theoretical insights into the reaction mechanisms remain limited. Our study investigates the influence of solvent polarity and halogen atom types on radical reaction pathways in EDA complexes. We demonstrate that solvent polarity modulates the charge transfer and spatial arrangement within EDA complexes, thereby influencing their stability and reaction kinetics. Iodide ions play a crucial role in facilitating free radical generation and stabilizing reaction intermediates. Different halogen atom types exhibit distinct effects on radical reactions. Variations in radical concentration and solvent environment further affect the pathway selectivity. Additionally, light conditions influence the free radical generation and pathway selectivity. Our findings enhance the understanding of EDA complex photochemistry and radical reactions, offering insights for organic synthesis and photochemistry applications.

Theoretical exploring effects of solvent polarity and atomic electronegativity on excited state behaviour for BY4TP fluorophore

As widely acknowledged, the realm of novel organic molecules boasting extraordinary attributes pertaining to excited-state intramolecular proton transfer (ESIPT) has emerged as a captivating subject matter. In this context, our primary focus lies in delving into the excited-state behaviour exhibited by 2-benzoxazol-2-yl-4-triethylsilanylethynyl-phenol (BY4TP), an alluring derivative derived from 2-(2-hydroxyphenyl)benzoxazole (HBO). Relying on the examination of four distinct aprotic solvents with varying degrees of polarities, we can unequivocally affirm that solvent polarity exerts a profound influence on the intricate interplay of hydrogen bonding interactions, charge redistribution and reorganisation, as well as associated ESIPT phenomena by light. Through meticulous comparison and precise measurement of reaction barriers across diverse solvent environments, our groundbreaking findings indicate that lowly polar solvents serve as efficacious facilitators for promoting the occurrence of the ESIPT reaction in BY4TP fluorophore. By considering atomic-electronegativity-regulated hydrogen bonding effects and excited state behaviours for BY4TP-S and BY4TP-Se, we also present low atomic electronegativity with Se substation promotes ESIPT reaction. We ardently anticipate that this study will provide invaluable insights into the behaviour exhibited by BY4TP upon excitation and under the influence of solvent polarity and atomic electronegativity, while simultaneously paving new avenues for future research endeavours and applications encompassing novel HBO derivatives.

Unraveling chemical glycosylation: DFT insights into factors imparting stereoselectivity

Stereoselective chemical glycosylation reactions are pivotal for preparing manifold biologically and medically important compounds, while mechanisms of chemical glycosylation reactions remain obscure and largely speculative. Herein, we performed DFT calculations to delve into the multifaceted mechanistic details of glycosylation reactions, including the equilibria among reactive glycosyl triflate intermediates in solution, the stereoselectivity imparting protecting groups, solvent effects, base, and the anomeric effect. Our results provided theoretical corroborations to 2-OAc neighbouring group participation (NGP), the arming/disarming effect, the coordination theory of solvent effect on glycosylation stereochemistry, and the influence of solvent polarity on the reaction kinetics spanning the SN1-SN2 continuum. For the first time, the existence of putative contact-ion-pairs (CIP) of glycosyl oxocarbenium and triflate anion in organic solutions was theoretically confirmed with the identification of multiple ground state structures employing an implicit Solvation Model based on Density (SMD). Kinetics of nucleophilic attack of model glucosyl triflates by simple alcohol acceptors ethanol (EtOH) and trifluoroethanol (TFE), complexed with 2,4,6-tri-tert-butylpyrimidine (TTBP) were explored, revealing the essential role of the close accompanying base for rendering glycosidic bond formation thermodynamically favorable. Our work deepens the comprehension of the glycosylation mechanism, paving the way for the rational design and future advancement of efficient and environmentally friendly stereoselective glycosylation reactions.

Theoretical insights into the impact of hydrogen bonding interactions and proton‐transfer phenomena on the excited state of HBT‐TMS fluorophore: Solvent‐induced effects

AbstractInspired by the design of distinguished optical materials, novel organic molecules exhibiting excited state intramolecular proton‐transfer (ESIPT) characteristics have emerged as a prominent research topic. In this study, we focus on investigating the excited state dynamics of 2‐(5‐trifluoromethyl‐benzothiazol‐2‐yl)‐4,6‐bis‐trimethylsilanylethynyl‐phenol (HBT‐TMS), a novel color‐tunable multifunctional ESIPT emitter. By considering four different aprotic solvents with varying polarities, we confirm the influence of solvent polarity on photo‐induced hydrogen bonding interactions, charge redistribution, and associated ESIPT phenomena. Through comparison and quantification of the magnitudes of excited state reaction barriers in different solvents, our findings suggest that highly polar solvents facilitate the ESIPT reaction for HBT‐TMS fluorophore.

Lessons learnt in photocatalysis – the influence of solvent polarity and the photostability of the photocatalyst

The triplet energies and redox properties of eight photocatalysts were found to vary a function of solvent polarity. Irrespective of solvent, the photocatalysts photodegraded under PET reaction conditions, but not PEnT reaction conditions.

Bioactive Compund Profile of Muntingia Calabura Leaf Extract with Different Polarity Solvent

The pursuit of bioactive compounds from natural sources for potential pharmaceutical and therapeutic applications remains a prominent focus of scientific investigation. Among the myriad of botanical treasures, M. calabura, colloquially known as the Jamaican cherry or strawberry tree, stands as an intriguing candidate, owing to its extensive historical utilization in folk medicine across diverse cultures. This study aimed to comprehensively characterize the bioactive compound profile of M. calabura leaves by employing a spectrum of solvents with varying polarities for extraction. The choice of solvent during extraction plays a pivotal role in determining both the types and quantities of compounds obtained from plant material. Our methodology encompassed cutting-edge analytical techniques, notably gas chromatography-mass spectrometry (GC-MS), to unravel the intricate chemical composition of the extracts derived from M. calabura leaves. Moreover, we scrutinized the potential influence of solvent polarity on extraction efficiency and subsequent bioactivity of the isolated compounds. Our findings underscore the profound impact of solvent selection on the repertoire of bioactive compounds extracted from M. calabura leaves. Polar solvents exhibited a proclivity for extracting compounds of higher polarity, while non-polar solvents favored the extraction of less polar constituents. The identification of prominent bioactive compounds within these extracts encompassed delta-tocopherol, 7-(γ,γ-dimethylallyloxy)flavanone, Wogonin, Neophytadiene, Octadecanoic acid, and Hexatriacontane, each with its own distinctive pharmacological significance. This study thus illuminates the critical role of solvent polarity in optimizing extraction processes and maximizing the therapeutic potential of M. calabura. The insights gleaned from this investigation not only contribute to our understanding of natural product chemistry but also hold the promise of inspiring the development of novel pharmaceutical agents and therapeutic interventions with wide-ranging applications.

Probing the Impact of Solvent on the Strength of Lewis Acids via Fluorescent Lewis Adducts.

Various methods have been developed to measure the strength of a Lewis acid. A major challenge for these measurements lies in the complexity that arises from variable solvent interactions and perturbations of Lewis acids as their reaction environment changes. Herein, we investigate the impact of solvent effects on Lewis acids for the first time as measured by the fluorescent Lewis adduct (FLA) method. The binding of a Lewis acid in various solvents reveals a measurable dichotomy between both polarity and donor ability of the solvent. While not strictly separable, we observe that the influence of solvent polarity on Lewis acid unit (LAU) values is distinctly opposite to the influence of donor ability. This dichotomy was confirmed by titration data, illustrating that solvation effects can be appropriately and precisely gauged by the FLA method.

Highly Efficient Triplet–Triplet Annihilation Upconversion with a Thermally Activated Delayed Fluorescence Molecule as Triplet Photosensitizer

Thermally activated delayed fluorescence (TADF) molecules have great potential for practical applications as triplet photosensitizers, owing to their long triplet lifetimes, almost negligible energy loss in intersystem crossing, and excellent light-harvesting ability. Recently, several triplet–triplet annihilation (TTA) upconversion systems using the TADF photosensitizer have been reported. To provide comprehensive dynamic information for designing an optimized system in the future, more experiments with the new TADF photosensitizers are necessary. Herein, we conducted a new TTA upconversion system with a recently developed TADF molecule, DMACPDO, as the triplet photosensitizer and 9,10-diphenylanthracene (DPA) as the annihilator. The overall upconversion yield was determined to be relatively high, e.g., 22.3% in toluene, 21.9% in benzene, and 8.1% in chlorobenzene. By examining elementary photophysical and photochemical processes with time-resolved transient absorption and fluorescence emission spectroscopy, we revealed the influence of solvent polarity and viscosity on each step. Our conclusion highlights the elusive solvent effect in TTA upconversion application of the TADF photosensitizer.

Role of the solvent polarity on the optical and electronic characteristics of 1-iodoadamantane.

The natural absorbance caused by the chromophore and chemical behavior of 1-iodoadamantane is highly influenced by the polarity of different solvent environments. This gives rise to the solvatochromatic shifts in the optical absorption and electronic structure and the experimentally measured UV-vis absorption spectra show significant solvatochromic shifts with respect to the solvent polarity. The absorption shift for both σ to σ*and n to σ* electronic transitions are more dominant in polar solvents than in nonpolar solvents. To obtain a better understanding of the impact of solvent polarity on the 1-iodoadamantane at the molecular level, computational calculations were carried out through implicit solvation. According to this, changes in the HOMO and LUMO energies and electron density distributions of various solvent continuums demonstrate the influence of solvent polarity on the HOMO and LUMO energy levels of the chemical system. This also shows an increment in the HOMO-LUMO gap with respect to the polarity of the solvent.

The investigation of the ultrafast excited state deactivation mechanisms for coumarin 307 in different solvents.

The intramolecular charge transfer (ICT) and twisted intramolecular charge transfer (TICT) processes of coumarin 307 (C307) in different solvents were investigated by performing steady-state/time-resolved transient absorption spectroscopic and steady-state photoluminescence spectroscopic characterizations in combination with time-dependent density functional theoretical calculation (TDDFT). The study unveiled the remarkable influence of solvent polarity and the strength of intermolecular hydrogen bonds formed between the solutes and solvents on the relaxation dynamics of the electronic excited state. Significantly, the emergence of the TICT state was observed in polar solvents, specifically dimethylformamide (DMF) and dimethyl sulfoxidemethanol (DMSO), owing to their inherent polarity as well as the enhanced intermolecular hydrogen bonding interactions. Interestingly, even in a weak polar solvent such as methanol (MeOH), the TICT state was also observed due to the intensified hydrogen bonding effects. Conversely, nonpolar solvents, exemplified by 1,4-dioxane (Diox), resulted in the stabilization of the ICT state due to the augmented N-H⋯O hydrogen bonding interactions. The experimental findings were corroborated by the computational calculations, thus ensuring the reliability of the conclusions drawn. Furthermore, schematic diagrams were presented to illustrate the mechanisms underlying the excited-state deactivation. Overall, this investigation contributes valuable mechanistic insights and provides a comprehensive understanding of the photochemical and photophysical properties exhibited by coumarin dyes.

Sustainable and effective approach to recover antioxidant compounds from purple tea (Camellia sinensis var. assamica cv. Zijuan) leaves

Camellia sinensis var. assamica cv. Zijuan (purple tea) is known for its content of anthocyanins, flavan-3-ols, and bioactivities. This study aimed to verify the influence of solvent polarity, in a solid–liquid extraction, on the content of phenolic compounds and chlorophylls, instrumental color, and antioxidant activity. Different proportions of water and ethanol (0:100, 25:75, 50:50, 75:25, and 100:0 v/v) were used for extraction. The results showed that the hydroalcoholic extract (75 % ethanol + 25 % water) had the highest contents of total flavonoids, total anthocyanins, chlorophyll A, and total carotenoids, as well as presenting the highest color intensity, proportion of yellow pigments, and antioxidant activity (total reducing capacity and scavenging of the DPPH free radical). Twenty-two compounds were identified, with chlorogenic acid, hesperidin, (-)-epicatechin, (-)-epigallocatechin gallate, and isoquercitrin being the main phenolics. This phenolic-rich extract inhibited lipoperoxidation induced in egg yolk homogenate (IC50 = 455 mg/L), showed no hemolytic behavior when human erythrocytes were subjected to osmotic stress, and exerted in vitro cytotoxic effects against cancer and hybrid cells. The extract obtained with the mixture of non-toxic solvents presented critical bioactivities, as well as a comprehensive identification of phenolic compounds in the cultivar, and has potential to be used in technological applications.

Experimental and theoretical studies of linear and non-linear optical properties of novel fused-triazine derivatives for advanced technological applications

Controlling photophysical properties is critical for the continued development of electroluminescent devices and luminescent materials. The preparation and study of novel molecules suitable as luminescent for the development of optoelectrical devices have recently received a lot of attention. Even though the as-triazine unit is a good building block for organic active substances, it is rarely used in this context. We created here novel bis-triazine derivative dyes in the far UV–Vis range by alkylation of triazine-thione derivatives with appropriate dibromo compounds. At the B3LYP/6-311**G(d,p) basis set, their optimal molecular structures were obtained. DFT technique confirmed that the new triazine derivatives are in noncoplanar with one of the two phenyl rings and the triazine plane rotating out by 102.09. Also, depending on the energy gap difference between HOMO and LUMO, some important parameters including chemical potential (π), electronegativity (χ), and chemical hardness (η) were calculated. The compounds may be readily polarized and have significant NLO characteristics, as seen by the tiny HOMO–LUMO energy gap. The calculated values for the polarizability (α) of the two new triazine derivatives have the range 6.09–10.75 × 10–24 (esu). The emission peaks seemed to move to the long-wavelength (redshift), with a rise in the fluorescence band, suggesting that the singlet excited state is more polar than the ground state. The influence of solvent polarity and the intermolecular charge transfer (ICT) processes are reflected in the photophysical properties of new fused triazine derivatives. These properties such as extinction coefficient, absorption and emission cross-sections, fluorescence quantum yield, fluorescence lifetime, oscillator strength, the dipole moment, radiative decay rate constant, the energy yield of fluorescence, and the attenuation length were assessed and discussed.

Uncovering the dependence of ESIPT behaviors and fluorescence properties of two new benzothiazole-based fluorophores on solvent polarity: A TD-DFT study

We have studied the spectral features and excited state intramolecular proton transfer (ESIPT) processes of 2-(2′,4′-dihydroxyphenyl)benzothiazole (OHBT) and 2-(2′-hydroxy-5′-chlorophenyl)benzothiazole (CHBT) using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). To consider the impact of solvent polarity and intermolecular hydrogen bond (H-bond) on the ESIPT behavior and photophysical properties, four solvents including toluene (TL), tetrahydrofuran (THF), methanol (MeOH) and dimethylsulfoxide (DMSO) were used. The simulated absorption and fluorescence wavelengths of OHBT and CHBT are well consistent with the experimental values. According to the results of structures, electron density and infrared (IR) vibrational frequencies, we found that the intramolecular H-bonds in OHBT/CHBT and OHBT-MeOH/CHBT-MeOH are strengthened in the first singlet excited state (S1), which will be benefical to the ESIPT process. The potential energy curves (PECs) verified that the ESIPT processes in OHBT/CHBT and OHBT-MeOH/CHBT-MeOH can take place much easier because of their lower energy barrier. The influences of solvent polarity on ESIPT behaviors and photophysical properties of OHBT and CHBT are summarized below. As the solvent polarity becomes stronger from TL to DMSO, the energy gaps enlarges a little, the maximum absorption and fluorescence peaks at normal form red-shift slightly, and the strengths of H-bond in S1 state become weaker, which makes the ESIPT process occur much harder. The formation of intermolecular H-bond between OHBT/CHBT and MeOH is conducive to promote the ESIPT process of OHBT/CHBT.

Investigation of atropisomeric transformation of a novel PDE4 inhibitor with tetrahydroisoquinoline-based amide group and its primary study of binding to HSA

In this study a kinetic and thermodynamic atropisomeric transformation due to a hindered rotation around the tetrahydroisoquinoline-based amide group was investigated. Quantum chemistry calculations were applied to investigate the transformation under the gas phase and several solvents with different polarity, and then evaluated by dynamic HPLC determination. It was found that the transformation rate of constants and the half-life time varied under the influence of solvent polarity and temperature and the energies of rotational barrier were determined ranging between 87 and 92 kJ∙mol−1. A primary binding study with HSA confirmed a rapid interconversion under the simulated physiological conditions. It is therefore suggested to take this atropisomeric compound as a racemic mixture for its future drug development.

Solvent controlled excited state intramolecular proton transfer (ESIPT) behavior and luminescent property of a novel phthalimide-based fluorophore: A TD-DFT Study

In view of density functional theory (DFT) and time-dependent DFT (TD-DFT) methods, we investigated the influence of solvent polarity on the excited state intramolecular proton transfer (ESIPT) behavior and spectral properties of 2‑butyl‑4-hydroxyisoindoline-1,3‑dione (BHD). In this work, five different solvents were selected: acetonitrile (MeCN), dichloromethane (DCM), tetrahydrofuran (THF), Benzene and n-Heptane. The experimental absorption and fluorescence wavelengths in MeCN were duplicated theoretically, which proved the reliability of the chosen method. The ESIPT process was easy to occur due to the enhanced intramolecular hydrogen bond (H-bond) in the excited state (S1), which has been confirmed by a series of results related to the H-bond. When the dielectric constant of solvent reduces, the influence of solvent polarity on spectral characteristics and ESIPT behavior included the following aspects: the ground state intramolecular H-bond strength and HOMO-LUMO energy gap became stronger and larger, respectively, while the corresponding parameters of excited state became weaker and smaller, respectively; the forward and reverse ESIPT barrier increased and decreased, respectively. Especially, the H-bond strength of S1 state and the red-shift value of O1H2 bond were linear with the dielectric constant of solvent.

Solvent polarity influence on chemiexcitation efficiency of inter and intramolecular electron-transfer catalyzed chemiluminescence

The parameters which determine the efficiency of chemiluminescence, and bioluminescence transformations are a continuous matter of experimental and theoretical studies. In this sense, we report here a study of the solvent polarity influence on four Chemically Initiated Electron Exchange Luminescence (CIEEL) systems. Two of them comprise intermolecular CIEEL systems with low efficiency – catalyzed decomposition of diphenoyl peroxide and spiroadamantyl-1,2-dioxetanone; the other two are highly efficient in producing excited states – the peroxyoxalate reaction through an intermolecular CIEEL, and the induced decomposition of a phenoxy-substituted 1,2-dioxetane derivative via intramolecular CIEEL. These four CIEEL systems are studied in binary solvent mixtures with similar viscosity but different polarity, as measured by the empirical solvent polarity parameter ET(30). Reaction rate constants for all the systems increase with increasing polarity, indicating the occurrence of electron or charge transfer in the rate-limiting step of these transformations. For the intermolecular systems, singlet quantum yields generally rise with medium polarity to a maximum value and decrease for higher polarities. This agrees with stabilization of the radical ion pair intermediate by solvation at an optimal medium polarity. In contrast, higher polarity promotes the separation of these charged species, thereby avoiding electron back-transfer between radical ion pairs, essential for chemiexcitation. The singlet quantum yields in the intramolecular CIEEL system show a steady increase with the medium polarity, reaching values close to the maximum possible quantum yield of 1.0 E mol−1, indicating the importance of biradical ion stabilization and the occurrence of the whole reaction sequence in an intramolecular manner.

Tailoring the SWIR emission of gold nanoclusters by surface ligand rigidification and their application in 3D bioimaging.

The influence of solvent polarity and surface ligand rigidification on the SWIR emission profile of gold nanoclusters with an anistropic surface was investigated. A strong enhancement of the SWIR emission band at 1200 nm was observed when measuring in different local environments: in solution, in polymer composites, and in solids. SWIR in vivo imaging of mice assisted by deep learning after intravenous administration of these gold nanoclusters provides high definition pseudo-3D views of vascular blood vessels.