Synthesis of Doubly Annulated m-Terphenyl-Based Molecular Tweezers and Their Charge-Transfer Complexes with DDQ as a Guest

Juggling Optoelectronics and Catalysis: The Dual Talents of Bench Stable 1,4-Azaborinines

Boron- and nitrogen-doped polycyclic aromatic hydrocarbons (B-PAHs) have established a strong foothold in the realm of organic electronics. However, their catalytic potential remains largely untapped. In this study, we synthesise and characterise two bench stable B,N-doped PAH derivatives based on a 1,4-azaborinine motif. Most importantly, the anthracene derived structure is an efficient catalyst in the reduction of various carbonyls and imines. These results underscore the potential of B,N-PAHs in catalytic transformations, setting the stage for deeper exploration in this chemical space.

Assembling Molecular Clips To Build π-Stacks

Nature utilizes an intimate stacking of aromatic motifs to construct functional structures, as demonstrated in protein folding and polynucleotide assembly. However, organized π-stacks of artificial molecules are difficult to build, primarily due to the weak, non-directional, and context-sensitive nature of van der Waals forces. To overcome these challenges, chemists have invented ingenious architectural designs to construct π-stacked supramolecular assemblies using clip-like molecules. This Concept article focuses on molecular clips that enable precise spatial control over assembly patterns, beyond the scope of simple host-guest chemistry. Different design strategies are analyzed and compared that leverage non-covalent interactions to create multi-layer π-stacks. Particular emphasis is placed on the choice of spine units as they play a crucial role in controlling the (i) spacing, (ii) orientation, and (iii) conformational pre-organization of linked aromatics to achieve long-range spatial ordering.

BN-Embedded Cycloarenes: One-Pot Borylation Synthesis, Photoelectric Properties, and Application in Perovskite Solar Cells

Incorporating heteroatoms, such as nitrogen, oxygen, and/or sulfur atoms, into cycloarenes can effectively regulate their molecular geometries and (opto)electronic properties. However, the rarity of cycloarenes and heterocycloarenes limits the further exploitation of their applications. Herein, we designed and synthesized the first examples of boron and nitrogen (BN)-doped cycloarenes (BN-C1 and BN-C2) via one-pot intramolecular electrophilic borylation of imine-based macrocycles. BN-C2 adopts a bowl-shaped conformation, while BN-C1 possesses a planar geometry. Accordingly, the solubility of BN-C2 was significantly improved by replacing two hexagons in BN-C1 with two N-pentagons, due to the creation of distortions away from planarity. Various experiments and theoretical calculations were carried out for heterocycloarenes BN-C1 and BN-C2, demonstrating that the incorporated BN bonds diminish the aromaticity of 1,2-azaborine units and their adjacent benzenoid rings but preserve the dominant aromatic properties of pristine kekulene. Importantly, when two additional electron-rich nitrogen atoms were introduced, the highest occupied molecular orbital energy level of BN-C2 was elaborately lifted compared with that of BN-C1. As a result, the energy-level alignment of BN-C2 with the work function of the anode and the perovskite layer was suitable. Therefore, for the first time, heterocycloarene (BN-C2) was explored as a hole-transporting layer in inverted perovskite solar cell devices, in which the power conversion efficiency reached 14.4%.

Fully Supramolecular Chiral Hydrogen-Bonded Molecular Tweezer

Molecular tweezers are open-ended, cavity-possessing U-shaped molecular architectures with high potential for various applications in supramolecular chemistry. Their covalent synthesis, however, is often tedious and the structures obtained lack structural responsiveness beyond the limited conformational flexibility of the scaffold. Herein we present a proof-of-concept study on the design, synthesis, assembly, and transformations of a novel supramolecular construct─a fully noncovalent molecular tweezer. The supramolecular tweezer was assembled from a set of four building blocks, composed of two identical molecular angle bars and two flat aromatic extension wings, using hydrogen bonding only. The chirality-assisted aggregation process was utilized to ensure scaffold bending directionality using enantiomerically pure bicyclic angle bars. To address the challenges associated with shifting of the equilibrium from strong cooperative narcissistic self-sorting of self-complementary angle bars in cyclic aggregates toward integrative self-sorting in molecular tweezers, a rational desymmetrization strategy was applied. The dynamic supramolecular tweezer has been shown to display rich supramolecular chemistry, allowing for stimuli-responsive change in aggregate topology and solvent-responsive supramolecular polymerization.

The role of natural biological macromolecules: Deoxyribonucleic and ribonucleic acids in the formulation of new stable charge transfer complexes of thiophene Schiff bases for various life applications

The ecofriendly cellulose and gelatin provided sustainable and abundant sugars: d-ribofuranose, and 2-Deoxy-ribofuranose (starting reactants for preparative synthetic green chemistry pathways of charge transfer complexes. The natural available sugars d-ribofuranose, and 2-Deoxy-ribofuranose were obtained from facile hydrolysis of cellulose and gelatin natural macromolecules. Successive, low cost and facile alkaline- and acid hydrolysis of Deoxyribonucleic acid (DNA, from gelatin animal source) and ribonucleic acid (RNA, from cellulose plant source) yield the simple sugars: d-ribofuranose and 2-Deoxy-ribofuranose. Eight optically and biologically active charge transfer complexes were prepared from the reaction of the above sugars efficiently intercalated with two new prepared thiophene Schiff Lewis (electron donors) bases: 2-((2Hydroxybenzylidene) amino)-4, 5, 6, 7-tetrahydrobenzo [b] thiophene-3-carbonitrile (D1, 2-((Furan-2ylmethylene) amino) 4,5,6,7 tetrahydrobenzo [b] thiophene-3-carbonitrile (D2). The chemical structures of these prepared Schiff bases were confirmed using the mass spectra. The successful intercalation of the sugar units with the Lewis bases was ascertained using powder x ray diffraction. The molecular structures of the reaction products were proposed based on FTIR, ¹H NMR. The optical activity of charge transfer complexes were confirmed using UV-Vis. Absorption spectroscopy. The surface morphology, microstructures, and particle size of the donors and charge transfer complexes were determined using scanning electron microscopy (SEM). The Lewis bases (D1) and (D2) showed no antimicrobial activity, while their charge transfer complexes showed good antimicrobial activity, suggesting their pharmaceutical and medicinal applications due to the potent biological activity against wide spread microbial microorganisms of Gram positive and Gram positive bacteria as well as some fungal species.

Electron-Transfer-Induced Self-Assembly of a Molecular Tweezer Platform

The design and synthesis of a new molecular tweezer (T-tmp) with electron-rich pincers are reported. The stable monocationic radicals and self-assembled dimeric radicals of this molecular tweezer platform were prepared by chemical oxidative titration. With the aid of DFT calculations, it was found that the dimeric radicals with syn-syn-syn conformer has the most stable structure, with the hole primarily delocalized between parallel stacked pyrenyl groups.