Controllable π-π coupling of intramolecular dimer models in aggregated states.

π-π coupling as a common interaction plays a key role in emissions, transport and mechanical properties of organic materials. However, the precise control of π-π coupling is still challenging owing to the possible interference from other intermolecular interactions in the aggregated state, usually resulting in uncontrollable emission properties. Herein, with the rational construction of intramolecular dimer models and crystal engineering, π-π coupling can be subtly modulated by conformation variation with balanced π-π and π-solvent interactions and visualized by green-to-blue emission switching.

Enhanced Gain in Organic Photodetectors Using the Polymer with Singlet Open-Shell Ground State.

Photodetectors are critical components in intelligent optoelectronic systems, and photomultiplication-capable devices are essential for detecting weak optical signals. Despite significant advances, developing photomultiplication-type organic photodetectors with high gain and low noise current simultaneously remains challenging. In this work, a new conjugated polymer PDN with singlet open-shell ground state is introduced in active layers for electron capture, and the corresponding PDN-based photodetectors exhibited an enhanced photoelectric gain and decreased dark current density at a low forward bias.

Organic Persistent RTP Crystals: From Brittle to Flexible by Tunable Self-Partitioned Molecular Packing.

Aiming to solve the trade-off of "room-temperature phosphorescence (RTP)-flexibility" in principle, organic RTP crystals with elastic/plastic deformation are realized. These properties are mainly due to the divisional aggregation structures of aromatics and alkoxy chains, and can be modulated by the controllable molecular configurations. The longest RTP lifetime of 972.

Expounding the Relationship between Molecular Conformation and Room-Temperature Phosphorescence Property by Deviation Angle.

Room-temperature phosphorescence (RTP) emitters with ultralong lifetimes are attracting more and more attention for their wide applications. However, it is still a big challenge to achieve persistent organic afterglow because of the undefined relationship between molecular structures and RTP effect. Herein, diphenylamine (DPA) as a commonly used building block is selected as the molecular skeleton.

Multi-photoresponsive triphenylethylene derivatives with photochromism, photodeformation and room temperature phosphorescence.

A series of triphenylethylene derivatives exhibited multi-photoresponsive properties, including photochromism, photodeformation and room temperature phosphorescence (RTP), which are strongly related to molecular conformations and packing in the aggregated states. Accordingly, these properties can be subtly adjusted by substituents to the center double bond and/or peripheral phenyl moieties. The introduction of bromine atom was beneficial to photochromism and photodeformation properties as a result of the additional C-H⋯Br interactions and electron-withdrawing property.

Tunable Photocontrolled Motions of Anil-Poly(ethylene terephthalate) Systems through Excited-State Intramolecular Proton Transfer and Trans-Cis Isomerization.

With the combination of excited-state intramolecular proton transfer and trans-cis isomerization as microscopic molecular motions under light stimulus, multiple photodeformable processes are achieved in anil-poly(ethylene terephthalate) systems, including simple bending, dancing butterflies, and switches. The doping films can realize light-driven contraction as large as 70% and bending angle of about 141°, upon a simple stretching process. The internal mechanism is confirmed by transient absorption spectra, and the relationship between molecular structure and photocontrolled motion is investigated by theoretical calculations and crystal analysis.

Mechanoluminescence or Room-Temperature Phosphorescence: Molecular Packing-Dependent Emission Response.

Mechanoluminescence (ML) and room-temperature photophosphorescence (RTP) were achieved in polymorphisms of a triphenylamine derivative with ortho-substitution. This molecular packing-dependent emission afforded crucial information to deeply understand the intrinsic mechanism of different emission forms and the possible packing-function relationship. With the incorporation of solid-state C NMR spectra of single crystals, as well as the analysis of crystal structures, the preferred packing modes for ML and/or RTP were investigated in detail, which can guide the reasonable design of organic molecules with special light-emission properties.