Intermolecular interaction energies and molecular conformations in N-substituted 4-aryl-2-methylimidazoles with promising in vitro antifungal activity

Current Advances in Diazoles-based Chemosensors for CN- and FDetection

Advances in molecular probes have recently intensified because they are valuable tools in studying species of interest for human health, the environment, and industry. Among these species, cyanide (CN-) and fluoride (F-) stand out as hazardous and toxic ions in trace amounts. Thus, there is a significant interest in probes design for their detection with diverse diazoles (pyrazole and imidazole) used for this purpose. These diazole derivatives are known as functional molecules because of their known synthetic versatility and applicability, as they exhibit essential photophysical properties with helpful recognition centers. This review provides an overview of the recent progress (2017-2021) in diazole-based sensors for CN- and F- detection, using the azolic ring as a signaling or recognition unit. The discussion focuses on the mechanism of the action described for recognizing the anion, the structure of the probes with the best synthetic simplicity, detection limits (LODs), application, and selectivity. In this context, the analysis involves probes for cyanide sensing first, then probes for fluoride sensing, and ultimately, dual probes that allow both species recognition.

X-ray structure, hirshfeld surfaces and interaction energy studies of 2,2-diphenyl-1-oxa-3-oxonia-2-boratanaphthalene

Single crystal XRD structure of the title compound reveals that the molecule adopt non-planar structure. The molecule is puckered with the total puckering amplitude of (Q) = 0.368(3)Å. Crystals of the title molecules are interconnected by intermolecular O–H⋯O and C–H⋯O interactions to develop 1D chains extending infinitely along the crystallographic a-axis. The intermolecular interactions were explored by Hirshfeld surfaces and their associated fingerprint graphs are obtained which revealed that the H⋯H and H⋯C pairs of inter atomic contacts were pre-dominant in the crystal packing of title compound. The energy of intermolecular interactions are computed using the accurate energy density model of B3LYP/6–31 G(d,p).

Influence of Steric Effect on the Pseudo-Multicomponent Synthesis of N-Aroylmethyl-4-Arylimidazoles

A pseudo-three-component synthesis of N-aroylmethylimidazoles 3 with three new C-N bonds formed regioselectively under microwave conditions was developed. Products were obtained by reacting two equivalents of aroylmethyl bromide (ArCOCH₂Br, 1) with the appropriate amidine salt (RCN₂H₃.HX, 2) and with K₂CO₃ as a base in acetonitrile. The bicomponent reaction also occurred, giving the expected 4(5)-aryl-1H-imidazoles 4. Notably, the ratio of products 3 and 4 is governed by steric factors of the amidine 2 (i.e., R = H, CH₃, Ph). Therefore, a computational study was carried out to understand the reaction course regarding product ratio (3/4), regioselectivity, and the steric effects of the amidine substituent group.

Chemosensors based on N-heterocyclic dyes: advances in sensing highly toxic ions such as CN- and Hg2

CN- and Hg2+ ions are harmful to both the environment and human health, even at trace levels. Thus, alternative methods for their detection and quantification are highly desirable given that the traditional monitoring systems are expensive and require qualified personnel. Optical chemosensors (probes) have revolutionized the sensing of different species due to their high specificity and sensitivity, corresponding with their modular design. They have also been used in aqueous media and different pH ranges, facilitating their applications in various samples. The design of molecular probes is based on organic dyes, where the key species are N-heterocyclic compounds (NHCs) due to their proven photophysical properties, biocompatibility, and synthetic versatility, which favor diverse applications. Accordingly, this review aims to provide an overview of the reports from 2016 to 2021, in which fluorescent probes based on five- and six-membered N-heterocycles are used for the detection of CN- and Hg2+ ions.

Conformational analysis of two new organotin(IV) structures completed with a CSD survey

The conformational flexibilities are studied in two new organotin(IV) complexes, namely, trans-dichloridodimethylbis[N,N',N''-tris(2-chlorobenzyl)phosphoric triamide]tin(IV), [Sn(CH₃)₂(C₂₁H₂₁Cl₃N₃OP)₂Cl₂] or Sn(CH₃)₂Cl₂{OP[NHCH₂C₆H₄(2-Cl)]₃}₂, (I), and bis(dipropylammonium) tetrachloridodimethylstannate(IV), [(CH₃CH₂CH₂)₂NH₂]₂[Sn(CH₃)₂Cl₄], (II), and their analogous structures from the Cambridge Structural Database (CSD). The conformations are considered based on the N-P=O-Sn torsion angles for (I) and the C-C-C-N, C-C-N-C, C-N-C-C and N-C-C-C torsion angles for the two symmetry-independent [CH₃CH₂CH₂NH₂CH₂CH₂CH₃]⁺ cations in (II), and the ±ac±sp±ac (ac = anticlinal and sp = synperiplanar) and ±ap±ap±ap±ap (ap = antiperiplanar) conformations are observed, respectively. In both structures, the four atoms in the corners of the square-planar segment of the octahedral shape around the Sn atom participate in normal hydrogen-bonding interactions as acceptors, which include two O and two Cl atoms for (I), and four Cl atoms for (II). However, the phosphoric triamide ligands block the environment around the Sn atom and limit the hydrogen-bond pattern to form a supramolecular ribbon assembly, while in the presence of small organic cations in (II), a two-dimensional hydrogen-bonded architecture is achieved. The weak interactions π-π, C-H...π and C-Cl...π in (I), and C-H...Cl in (II) do not change the dimensionality of the hydrogen-bond pattern. The 62 CSD structures analogous to (I), i.e. with an SnOPN₃ segment (including 83 entries) fall into four categories of conformations based on the N-P=O-Sn torsion angles. The 132 [(CH₃CH₂CH₂)₂NH₂]⁺ cations from 85 CSD structures are classified into seven groups based on the torsion angles noted for (II). Most of the CSD structures adopt the same associated conformations noted for (I) and (II). 15 [Sn(CH₃)₂Cl₄]^2- anions extracted from the CSD are compared with the structure of (II).

Pyrazolo[1,5-a]pyrimidines-based fluorophores: a comprehensive theoretical-experimental study

Fluorescent molecules are crucial tools for studying the dynamics of intracellular processes, chemosensors, and the progress of organic materials. In this study, a family of pyrazolo[1,5-a]pyrimidines (PPs) 4a-g has been identified as strategic compounds for optical applications due to several key characteristics such as their simpler and greener synthetic methodology (RME: 40-53%) as compared to those of BODIPYS (RME: 1.31-17.9%), and their tunable photophysical properties (going from ε = 3320 M^-1 cm^-1 and ϕ _F = 0.01 to ε = 20 593 M^-1 cm^-1 and ϕ _F = 0.97), in which electron-donating groups (EDGs) at position 7 on the fused ring improve both the absorption and emission behaviors. The PPs bearing simple aryl groups such as 4a (4-Py), 4b (2,4-Cl₂Ph), 4d (Ph) and 4e (4-MeOPh), allow good solid-state emission intensities (QY_SS = 0.18 to 0.63) in these compounds and thus, solid-state emitters can be designed by proper structural selection. The properties and stability found in 4a-g are comparable to commercial probes such as coumarin-153, prodan and rhodamine 6G. Ultimately, the electronic structure analysis based on DFT and TD-DFT calculations revealed that EDGs at position 7 on the fused ring favor large absorption/emission intensities as a result of the ICT to/from this ring; however, these intensities remain low with electron-withdrawing groups (EWGs), which is in line with the experimental data and allows us to understand the optical properties of this fluorophore family.