Based on rotational dynamics measurements carried out with isomorphic co-crystals formed by halogen-bonding (XB) between tritylacetylene halides (TrX) and diazabicyclo[2.2.2]octane (dabco), we were able to distinguish the sources of enthalpic entropic components in free energy barrier. We describe formation 1:1 (TrX···N(R)3N) obtained from 1 equiv dabco either TrI or TrBr, respectively, give 4a 4b instead potential 2:1 complexes. The prepared solvent evaporation mechanochemical synthesis. No...

Alpha-oxoamides 1 with o-tert-butyl substitution on the N-phenyl moiety were found to be stable axially chiral atropisomers. These alpha-oxoamides undergo enantiospecific photochemical gamma-Hydrogen abstraction in CHCl(3) yield beta-lactams high enantioselectivity (e.r. approximately 90:10) solution. The extent of was dependent reaction temperature.

It is recognized that metal organic complexes serve as sensitizers can present various degrees of challenges viz. synthesis and stability for photonic applications such triplet-triplet annihilation based photon upconversion (TTA-PUC). Presently, researchers, including our group, are turning their attention toward purely triplet sensitizers, which be handled more easily management science. In this review, we surveyed recently developed all-organic chromophoric systems were devised used...

ConspectusPhotochemical transformations are a powerful tool in organic synthesis to access structurally complex and diverse synthetic building blocks. However, this great potential remains untapped the mainstream community due challenges associated with stereocontrol originating from excited state(s). The finite lifetime of an state nearly barrierless subsequent processes present significant manipulating stereochemical outcome photochemical reaction. Several methodologies were developed...

The photochemical properties and reaction mechanisms were studied for a series of hypervalent iodo-azide compounds (R-IN₃), with substituents (-CH₃, -H, -CF₃) modulating electronic density in the phenyl ring. With help UV irradiation, ultrafast time-resolved spectroscopy, functional theory (DFT) calculations, we elucidate azide radical (N₃•) release its subsequent reactivity. UV/Vis spectroscopy reveals that photo-conversion rates follow trend CH₃ > H CF₃, aligning DFT-calculated ΔG...

Molecularly chiral o-tert-butylacrylanilides undergo enantiospecific 6pi-photocyclization to yield 3,4-dihydroquinolin-2-ones with very high enantioselectivity (>90%) in solution. The photocyclization results the removal of ortho tert-butyl substituent, presumably via a zwitterionic intermediate. Beta-substitution alkene is found be critical for transfer molecular chirality (axial chirality) reactant point photoproduct(s).

The enantiomeric ratio (e.r.) in the 3,4-dihydroquinolin-2-one photoproduct during 6π-photocyclization of α-substituted axially chiral ortho-tert-butyl-acrylanilides depends on nature reactive spin state (singlet or triplet), where singlet-spin reactivity gives a racemic mixture and triplet an e.r. value >95 : 5.

The COVID-19 pandemic has emphasized the urgency for effective antiviral therapies against SARS-CoV-2. Targeting main protease (3CLpro) of virus emerged as a promising approach, and nirmatrelvir (PF-07321332), active component Pfizer's oral drug Paxlovid, demonstrated remarkable clinical efficacy. However, emergence resistance mutations poses challenge to its continued success. In this study, we employed alchemical free energy perturbation (FEP) alanine scanning identify...

Abstract Enantiospecific axial‐to‐point chiral transfer in light‐induced transformations was efficient under elevated pressure at high temperatures. Model photoreactions with atropisomeric compounds showed higher enantioselectivity the photoproducts pressure. The ee values were rationalized based on increased stability of optically pure pressure, even

Donor–acceptor dyads are promising materials for improving triplet-sensitized photon upconversion due to faster intramolecular energy transfer (ET), which unfortunately competes with charge (CT) dynamics. To circumvent the issue associated CT, we propose a novel purely organic donor–acceptor dyad, where CT character is confined within donor moiety. In this work, report synthesis and characterization of stable radical donor-triplet acceptor dyad (TTM–Cz–Per) consisting perylene (Per) linked...

We report a novel reductive desulfurization reaction involving π-acidic naphthalene diimides (NDI) 1 using thionating agents such as Lawesson's reagent. Along with the expected thionated NDI derivatives 2–6, new heterocyclic naphtho-p-quinodimethane compounds 7 depicting broken/reduced symmetry were successfully isolated and fully characterized. Empirical studies theoretical modeling suggest that was formed via six-membered ring oxathiaphosphenine intermediate rather than usual four-membered...

Light-induced transformation of atropisomeric and achiral enones displays divergent reactivity. Photocyclization leading to 3,4-dihydroquinolin-2-one was observed with enone carboxamide, whereas the carboxamides underwent hydrogen abstraction spiro-β-lactams. Detailed photochemical, photophysical, theoretical investigations have provided insight into this reactivity selectivity.

A naphtho-p-quinodimethane (QDM) exhibiting Baird's 4n – π antiaromaticity was used as green photons-harvesting chromophore to sensitize perylene (Per) leading upconverted blue photoluminescence. The solution phase QDM → Per triplet energy transfer (TET) could not be unraveled via the Stern–Volmer method, but transient absorption measurements revealed that kinetics of T1 Tn for (τ = 1.4 μs) 1 order magnitude reduced 0.17 a result 3(Per)* formation. Furthermore, we demonstrated incident light...

Aqueous suspensions of nanocrystals in the 200-500 nm size range isostructural α-(ortho-tolyl)-acetophenone (1a) and α-(ortho-tolyl)-para-methylacetophenone (1b) displayed good absorption characteristics for flash photolysis experiments a flow system, with transient spectra decay kinetics quality that is similar to recorded solution. In contrast solution measurements, reactions solid state were characterized by rate limiting hydrogen transfer reaction from triplet excited very short-lived...

The nanosecond electronic spectra and kinetics of the radical pairs from various crystalline tetraarylacetones were obtained using transmission laser flash photolysis methods by taking advantage aqueous nanocrystalline suspensions in presence submicellar CTAB, which acts as a surface passivator. After showing that all react efficiently photodecarbonylation reaction state, we able to detect intermediate within ca. 8 ns pulse our setup. We showed solid-state are very similar those detected...

Abstract We report two new organic green‐absorbing singlet oxygen ( 1 O 2 ) photosensitizers: Quinoidal naphthyl thioamide QDM and bis ‐iodol‐dipyrrolonaphthyridine‐dione I – DPND ), with triplet energies of 40.8 47.5 kcal mol −1 (at 77 K in a glassy matrix) , respectively. The UV–vis absorption emission characteristics are similar to other commercially available photosensitizers such as Rose Bengal, which was used standard/reference estimate the quantum yield (Φ ∆ chromophores under study....

We report the synthesis and photophysical characterization of a triplet donor–acceptor dyad (3), which was constructed from quinoidal naphthalene thioamide sensitizer 1 perylene derivative 2 as acceptor. The interest exhibits convoluted characteristics donor acceptor chromophores. kinetic analysis phosphorescence 3 produced two lifetimes τ1 = 1.1 ms τ2 20 ms. shorter component attributed to lifetime 3(1)* moiety (within dyad) longer can be assigned either state 3(2)* or charge transfer (CT)*...

Aqueous nanocrystalline suspensions provide a simple and efficient medium for performing transmission spectroscopy measurements in the solid state. In this Letter we describe use of laser flash photolysis methods to analyze photochemistry 2-azidobiphenyl several aryl-substituted derivatives. We show that all crystalline compounds analyzed study transform quantitatively into carbazole products via crystal-to-crystal reconstructive phase transition. While initial steps reaction cannot be...