CCDC 2022503: Experimental Crystal Structure Determination

Related Article: Cory T. Kornman, Lei Li, Asmerom O. Weldeab, Ion Ghiviriga, Khalil A. Abboud, Ronald K. Castellano|2020|Chemical Science|11|10190|doi:10.1039/D0SC04409

Enlightening the Well-Controlled Photochemical Behavior of 1,1-Dicyanomethylene-3-Indanone-Functionalized π‑Conjugated Molecules

1,1-Dicyanomethylene-3-indanone (INCN) is a popular electron acceptor showcased in hundreds of push–pull oligomers, including some of the best nonfullerene acceptor (NFA) materials used in small molecule-based bulk-heterojunction (BHJ) organic photovoltaics (OPVs). Consequences of the configuration (i.e., Z or E) and conformation (i.e., s-cis or s-trans) of the exocyclic olefin that conjugates INCN to π-conjugated molecules have largely been ignored. Two recent reports have implicated Z/E photoisomerization in the photodegradation of popular NFAs like IT-4F when subjected to broad spectrum irradiation. Here, we elucidate through experiments and complementary ground- and excited-state computations the photochemical behavior of a family of eight INCN-functionalized donor–acceptor molecules varying in aryl and heteroaryl substitution, alkyl group substitution, and halogen functionalization on the INCN unit. Well-controlled Z/E photoisomerization using selective wavelengths of excitation spanning the ultraviolet and visible regions is observed in all cases yielding a range of Z/E photostationary state (PSS) distributions with no evidence of a previously reported photooxidation. Z/E photoisomerization followed by sequential pericyclic reactions, consistent with one recent literature report, is identified for just one target molecule upon irradiation at 454 nm. The alkyl group positioning on the thiophene ring neighboring the INCN is found to bias the conformational preferences of the target molecules and modulate access to this reaction pathway. All eight molecules undergo facile Z/E photoswitching over numerous cycles upon selective excitation. Overall, the work reveals the well-controlled photochemical behavior of INCN-functionalized π-systems and encourages their use in the design of future functional and organic materials and photoswitches

Synthesis and Evaluation of 3-Halobenzo[<i>b</i>]thiophenes as Potential Antibacterial and Antifungal Agents

The global health concern of antimicrobial resistance has harnessed research interest to find new classes of antibiotics to combat disease-causing pathogens. In our studies, 3-halobenzo[b]thiophene derivatives were synthesized and tested for their antimicrobial activities using the broth microdilution susceptibility method. The 3-halo substituted benzo[b]thiophenes were synthesized starting from 2-alkynyl thioanisoles using a convenient electrophilic cyclization methodology that utilizes sodium halides as the source of electrophilic halogens when reacted along with copper(II) sulfate. This environmentally benign methodology is facile, uses ethanol as the solvent, and results in 3-halo substituted benzo[b]thiophene structures in very high yields. The cyclohexanol-substituted 3-chloro and 3-bromobenzo[b]thiophenes resulted in a low MIC of 16 µg/mL against Gram-positive bacteria and yeast. Additionally, in silico absorption, distribution, metabolism, and excretion (ADME) properties of the compounds were determined. The compounds with the lowest MIC values showed excellent drug-like properties with no violations to Lipinski, Veber, and Muegge filters. The time-kill curve was obtained for cyclohexanol-substituted 3-chlorobenzo[b]thiophenes against Staphylococcus aureus, which showed fast bactericidal activity at MIC

Structure–Assembly–Property Relationships of Simple Ditopic Hydrogen-Bonding-Capable π-Conjugated Oligomers

Abstract A series of simple ditopic hydrogen-bonding-capable molecules functionalized with 2,4-diamino-1,3,5-triazine (DAT), barbiturate (B), and phthalhydrazide (PH) on both termini of a 2,2′-bithiophene linker were designed and synthesized. The intrinsic electronic structures of the ditopic DAT, PH, and B molecules were investigated with ground-state density functional theory calculations. Their solution absorbance was investigated with UV-vis, where it was found that increasing size of R group substituents on the bithiophene linker resulted in a general blue-shift in solution absorbance maximum. The solid-state optical properties of ditopic DAT and B thin films were evaluated by UV-vis, and it was found that the solid-state absorbance was red-shifted with respect to solution absorbance in all cases. The three DAT molecules were vacuum-thermal-deposited onto Au(111) substrates and the morphologies were examined using scanning tunneling microscopy. (DAT-T)2 was observed to organize into six-membered rosettes on the surface, whereas (DAT-TMe)2 formed linear assemblies before and after thermal annealing. For (DAT-Toct)2 , an irregular arrangement was observed, while (B-TMe)2 showed several co-existent assembly patterns. The work presented here provides fundamental molecular–supramolecular relationships useful for semiconductive materials design based on ditopic hydrogen-bonding-capable building blocks