A van der Waals porous crystal featuring conformational flexibility and permanent porosity for ultrafast water release.

Flexibility has been pursued enthusiastically in the field of porous crystals for enhancing their adsorption and separation performances. However, flexibility has never been observed among porous crystals sustained thoroughly by van der Waals interactions since flexible motions readily lead to the collapse of the porous architecture. Here we report a van der Waals crystal featuring conformational flexibility as well as permanent microporosity.

Tuneable stimuli-responsive behaviour, spectroscopic signatures and redox properties of indolo[3,2-]carbazole-based diradicals.

During the last decade, there has been an increasing interest in the rationalisation of how structural changes stabilise (or destabilise) diradical systems. Demonstrated herein is that indolocarbazole (ICz) diradicals, substituted with dicyanomethylene (DCM) groups, are useful motifs for dynamic covalent chemistry by self-assembling from isolated monomers to cyclophane structures. The comparison of ICz-based systems substituted with DCM groups in - or -positions (p-ICz-CN and m-ICz-CN) and their short-chain carbazole analogues (p-Cz-CN and m-Cz-CN) may identify new potential design strategies for stimuli-responsive materials.

Understanding the Raman enhancement of carbon nanohorns labelled with organic dyes.

Carbon nanohorns have been non-covalently functionalized with two different benzothiadiazoloquinoxalines prepared Stille cross-coupling reactions under solvent-free conditions and microwave irradiation. The close interactions between these organic molecules and the nanostructures resulted in a prominent Raman enhancement, which makes them attractive candidates for multiple applications. A complete experimental physico-chemical characterization has been combined with studies to understand these phenomena.

Molecular Tuning in Diaryl-Capped Pyrrolo[2,3-:5,4-']bisthiazoles: Effects of Terminal Aryl Unit and Comparison to Dithieno[3,2-:2',3'-]pyrrole Analogues.

A series of six conjugated oligomers consisting of a central pyrrolo[2,3-:5,4-']bisthiazole (PBTz) end-capped with either thienyl, furyl, or phenyl groups have been prepared from -alkyl-and -aryl-pyrrolo[2,3-:5,4-']bisthiazoles via Stille and Negishi cross-coupling. The full oligomeric series was thoroughly investigated via photophysical and electrochemical studies, in parallel with density functional theory (DFT) calculations, in order to correlate the cumulative effects of both aryl end-groups and -functionalization on the resulting optical and electronic properties. Through comparison with the analogous dithieno[3,2-:2',3'-]pyrrole (DTP) materials, the effect of replacing DTP with PBTz on the material HOMO energy and visible light absorption is quantified.

Tuning the Diradical Character of Indolocarbazoles: Impact of Structural Isomerism and Substitution Position.

In this study, a set of 10 positional indolocarbazole (ICz) isomers substituted with dicyanomethylene groups connected via or positions are computationally investigated with the aim of exploring the efficiency of structural isomerism and substitution position in controlling their optical and electronic properties. Unrestricted density functional theory (DFT), a spin-flip time-dependent DFT approach, and the multireference CASSCF/NEVPT2 method have been applied to correlate the diradical character with the energetic trends (i.e.

Probing the nature of donor-acceptor effects in conjugated materials: a joint experimental and computational study of model conjugated oligomers.

A series of model oligomers consisting of combinations of a traditional strong donor unit (3,4-ethylenedioxythiophene), a traditional strong acceptor unit (benzo[][1,2,5]thiadiazole), and the ambipolar unit thieno[3,4-]pyrazine were synthesized cross-coupling methods. The prepared oligomers include all six possible dimeric combinations in order to characterize the extent and nature of donor-acceptor effects commonly used in the design of conjugated materials, with particular focus on understanding how the inclusion of ambipolar units influences donor-acceptor frameworks. The full oligomeric series was thoroughly investigated photophysical and electrochemical studies, in parallel with density functional theory (DFT) calculations, in order to correlate the nature and extent of donor-acceptor effects on both frontier orbital energies and the desired narrowing of the HOMO-LUMO energy gap.

Dynamic Covalent Properties of a Novel Indolo[3,2-b]carbazole Diradical.

This work describes the synthesis and properties of a dicyanomethylene-substituted indolo[3,2-b]carbazole diradical ICz-CN. This quinoidal system dimerises almost completely to (ICz-CN) , which contains two long C(sp )-C(sp ) σ-bonds between the dicyanomethylene units. The minor open-shell ICz-CN component in the solid-state mixture was identified by EPR spectroscopy.

Cyclization-Promoted Ultralong Low-Temperature Phosphorescence via Boosting Intersystem Crossing.

Ultralong organic phosphorescence holds great promise as an important approach for optical materials and devices. Most of phosphorescent organic molecules with long lifetimes are substituted with heavy atoms or carbonyl groups to enhance the intersystem crossing (ISC), which requires complicated design and synthesis. Here, we report a cyclization-promoted phosphorescence phenomenon by boosting ISC.

Sigmoidally hydrochromic molecular porous crystal with rotatable dendrons.

Vapochromic behaviour of porous crystals is beneficial for facile and rapid detection of gaseous molecules without electricity. Toward this end, tailored molecular designs have been established for metal-organic, covalent-bonded and hydrogen-bonded frameworks. Here, we explore the hydrochromic chemistry of a van der Waals (VDW) porous crystal.