Absolute Saturation Vapor Pressures of Three Fatty Acid Methyl Esters around Room Temperature

ACS Omega, Journal Year: 2025, Volume and Issue: 10(7), P. 6671 - 6678

Published: Feb. 11, 2025

We report measurements of absolute saturation vapor pressures around room temperature for three fatty acid methyl esters (methyl octanoate, decanoate, and dodecanoate) using a recently developed experimental method in which the are determined from vaporization dynamics cooled sample during thermalization to higher chamber temperature.

Language: Английский

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Abiotic Ribonucleoside Formation in Aqueous Microdroplets: Mechanistic Exploration, Acidity, and Electric Field Effects

ChemistryEurope, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 9, 2025

Abstract Aqueous microdroplets have been reported to dramatically increase the rate of chemical reactions. Proposed mechanisms for this acceleration include confinement effects upon droplet evaporation, and Brønsted acid or electric field catalysis at air‐water interface. However, computational investigations indicate that operation these is reaction‐dependent, with conclusive evidence a role still lacking. Here, we present investigation abiotic phosphorylation ribose subsequent formation ribonucleosides, focusing on acidity oriented external (OEEF) effects. The most plausible reaction mechanism identified involves protonation ribose, followed by carbocation an S N 2 substitution step. Without OEEF, all considered pathways are thermally inaccessible. in presence significant 2‐based pathway, leading β ‐ribonucleoside isomer, becomes highly stabilized, reducing energetic span accessible 12–13 kcal/mol. Surprisingly, OEEF‐mediated closely mirrors enzymatic phosphorolysis via substitution, including pronounced anomeric selectivity. Our results support hypothesis some reactions aqueous accelerated fields provide further importance electrostatic biological systems, particularly phosphorylase enzymes.

Language: Английский

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Using Conformational Sampling to Model Spectral and Structural Changes of Molecules at Elevated Pressures

The Journal of Physical Chemistry A, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 12, 2025

Conformational sampling is nowadays a standard routine in computational chemistry. Within this work, we present method to perform conformational for systems exposed elevated pressures within the CREST program, allowing us model pressure-induced changes of molecular ensembles and structural parameters. For purpose, extend Hamiltonian with PV (pressure times volume) term, using solvent-accessible volume. The volume computation performed new standalone library libpvol. A first application shows good agreement experimental data provides reasonable explanation severe spectroscopic molecules dichloroethane tetra(4-methoxyphenyl)ethylene.

Language: Английский

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Chiroptical Spectroscopy, Theoretical Calculations, and Symmetry of a Chiral Transition Metal Complex with Low-Lying Electronic States

Molecules, Journal Year: 2025, Volume and Issue: 30(4), P. 804 - 804

Published: Feb. 10, 2025

Vibrational circular dichroism (VCD) enhancement by low-lying electronic states (LLESs) is a fascinating phenomenon, but accounting for it theoretically remains challenge despite significant research efforts over the past 20 years. In this article, we synthesized two transition metal complexes using tetradentate Schiff base ligands (R,R)- and (S,S)-N,N'-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine with Co(II) Mn(III), referred to as Co(II)-salen-chxn Mn(III)-Cl-salen-chxn, respectively. Their stereochemical properties were explored through combined experimental chiroptical spectroscopic theoretical approach, focus on Co(II)-salen-chxn. Extensive conformational searches in CDCl3 both high- low-spin carried out associated infrared (IR), VCD, ultraviolet-visible (UV-Vis) absorption, (ECD) spectra simulated. A good agreement between simulated data was achieved IR, UV-Vis, ECD, except case of VCD which exhibits intensity monosignate bands, attributed LLESs. Interestingly, detailed comparisons Mn(III)-Cl-salen-chxn previously reported Ni(II)-salen-chxn Cu(II)-salen-chxn suggest that factor predicted current density functional theory simulations. However, signatures observed spectrum not captured theoretically. Based experiment ECD comparison, tentatively suggested exists low- high-spin states, former being dominant, while state. The study indicates LLESs at least partially existing simulation, symmetry consideration vibronic coupling provides further insight into mechanisms behind sign-flip.

Language: Английский

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Polymer Matrix Drives Dual Phosphorescence in Dispersed Chromophores

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 13, 2025

Poly(methyl methacrylate) (PMMA) matrix has been extensively explored for decades to achieve efficient room-temperature phosphorescence in blue-to-red regions from dispersed chromophores. Isolated chromophores at low-weight concentrations the polymer eliminate inter-chromophore interactions. However, impact of on optical characteristics remains elusive. Herein, we analyze dual behavior three molecularly (1 wt.% concentration) PMMA matrix. We employ second-order Algebraic Diagrammatic Construction (ADC2) excited state calculations show that observed BANHPh and BANMePh does not stem T₁ T₂ electronic states. Instead, this phenomenon arises matrix-assisted, accessible conformers within (T₁^H T₁^L). The creates an asymmetric environment around chromophores, inducing structural modulations result spectral tuning singlet triplet manifolds. In conclusion, conformation-dependent is unlikely occur without These matrix-induced phosphorescent emitters have demonstrated be highly competent application fingerprint recognition, information encryption, afterglow display.

Language: Английский

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