Photoluminescent materials, that are now ubiquitous in our everyday life, have particularly attracted the attention of the scientific community these past few years due to potential important applications such as in bioimaging, sensing, or optoelectronics. In this context, relatively few different families of molecules have been reported to exhibit fluorescence in the aggregated or solid-state through the excited-state intramolecular proton transfer (ESIPT) photochemical process. The preparation and subsequent determination of photochemical properties of an underexplored family of 1,5-benzodiazepin-2-one derivatives are reported. From these data and X-ray diffraction analysis study, it emerged that photoluminescence (in the range 520-655 nm) was mostly attributed to ESIPT. The photoluminescent potential of 1,5-benzodiazepin-2-ones, their facile access, and functionalization were demonstrated through the preparation of two fluorogenic probes for the selective detection of biothiols.

The present work arose out of a desire to fundamentally understand the molecular geometry, weak interactions, electron density delocalization, and chemical reactivity features of 1,5‐benzodiazepines‐containing family. Herein, a complete X‐ray crystallographic study, supported by trustworthy sets of computational approaches, has been reported for two organic crystals. Quantifying intramolecular and intermolecular interactions by Hirshfeld‐Becke surfaces analysis conjointly with noncovalent interaction‐reduced density gradient topological study revealed that supramolecular assemblies are stabilized by N‐H …O (inter) and O‐H …N (intra) hydrogen bonds, Cg …Cg (π …π) and C‐H(O) …π intercontacts, as well as Van der Waals interactions and steric effects. The long‐range‐corrected functional wB97XD, which uses Grimme's D2 dispersion model, seems to be just right for our systems. The quantum theory of atoms in molecules analysis confirms that both significant O1‐H1…N1 and N2‐H2A…O2 H‐bonds are weak and electrostatic in nature. Furthermore, global reactivity indices computed via the conceptual density functional theory framework allows these molecules to be classified as moderate electrophiles and marginal nucleophiles. The active sites favorable for nucleophilic/electrophilic attacks were also predicted based on local Parr functions. Finally, a comparative evaluation on the aromaticity character and π‐π stacking ability has been done for different (pseudo) rings.

Abstract:The CuI-or Ag 2 CO 3 -catalyzed [3+2] cycloaddition of propargyl-substituted dihydroisoindolin-1-one (3) with arylnitrile oxides 1a-d (Ar = Ph, p-MeC 6 H 4 , p-MeOC 6 H 4 , p-ClC 6 H 4 ) produces in good yields novel 3,5-disubstituted isoxazoles 4 of the ethyl-2-benzyl-3-oxo-1-((3-arylisoxazol-5yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylate type. With aryl azides 2a-d (Ar = Ph, p-MeC 6 H 4 , p-OMeC 6 H 4 , p-ClC 6 H 4 ), a series of 1,4-disubstituted 1,2,3-triazoles 6 (ethyl-2-benzyl-3-oxo-1-((1-aryl-1H-1,2,3-triazol-4-yl)methyl)-2,3-dihydro-1H-isoindole-1-carboxylates) was obtained. The reactions proceed in a regioselective manner affording exclusively racemic adducts 4 and 6. Compared to the uncatalyzed cycloaddition, the yields are significantly improved in the presence of CuI as catalyst, without alteration of the selectivity. The regio-and stereochemistry of the cycloadducts has been corroborated by an X-ray diffraction study of 4a, and in the case of 6a by XH-correlation and HMBC spectra.

A novel and practical synthesis of 3-benzoylquinoxalin-2(1H)-ones from benzodiazepin-2-ones in two steps from commercially available starting materials is reported. The reaction was achieved in the presence of N-bromosuccinimide in DMSO which served both as a solvent and an oxidant. Significantly, the yet unknown ketone to alcohol fluorescence turn-on of benzoylquinoxalinones was unveiled through the preparation of a fluorescently labelled cholesterol conjugate.

No abstract