Probing the Design Rules for Optimizing Electron Spin Relaxation in Densely Packed Triplet Media for Quantum Applications

Quantum technologies using electron spins have the advantage of employing chemical qubit media with tunable properties. The principal objective of material engineers is to enhance photoexcited spin yields and quantum spin relaxation. In this study, we demonstrate a facile synthetic approach to control spin properties in charge-transfer cocrystals consisting of 1,2,4,5-tetracyanobenzene (TCNB) and acetylated anthracene. We find that the extent and position of acetylation control the degree of charge-transfer and the optical band gap by modifying crystal packing and electronic structure. We further reveal that while the spin polarization of the triplet state is slightly reduced compared to prototypical Anthracene:TCNB, the phase memory (T m) and, for 9-acetylanthracene:TCNB spin-lattice relaxation (T 1) time, could be enhanced up to 2.4 times. Our findings are discussed in the context of quantum microwave amplifiers, known as masers, and show that acetylation could be a powerful tool for improving organic materials for quantum sensing applications.

Charge Transfer Dynamics in Supramolecular Tessellations Composed of Aromatic Donors and Chiral Tris(naphthalenediimide) Triangular Acceptors

Understanding charge transfer (CT) dynamics in donor-acceptor (D-A) cocrystals is important for the development of efficient organic photovoltaic and electronic materials. This study explores the photogenerated CT states of supramolecular tessellations formed by cocrystallizing a chiral tris(naphthalenediimide) triangular prism (-)-NDI-Δ with pyrene, perylene, and peri-xanthenoxanthene electron donors. By manipulating crystallization conditions, one-dimensional (1D) and two-dimensional (2D) cocrystals with distinct structural motifs and morphologies are achieved. Femtosecond and nanosecond transient absorption microscopies and time-resolved electron paramagnetic resonance spectroscopy were employed to elucidate the CT state dynamics. Our findings reveal that the CT state lifetimes are lengthened in the 2D cocrystals relative to the 1D cocrystals, which is attributable to the symmetry and molecular packing differences between them that modulate the CT interactions. This work highlights the potential of using preorganized covalent multisite charge carriers as donors or acceptors in cocrystals as a strategy for engineering structures for advanced multifunctional materials with tunable CT properties.

Remotely Modulating the Optical Properties of Organic Charge-Transfer Crystallites via Molecular Packing

Organic charge-transfer complex (CTC) formation has emerged as an effective molecular engineering strategy for achieving the desired optical properties via intermolecular interactions. By synthesizing organic CTCs with carbazole-based electron donors and a 7,7,8,8-tetracyanoquinodimethane acceptor and adopting a molecular linker located remotely from the charge-transfer interface within the donors, we were able to modulate near-infrared absorptive and short-wavelength infrared emissive properties. Structural characterizations performed by using single-crystal X-ray diffraction confirmed that the unique molecular arrangements induced by the steric hindrance from the remotely located linker significantly influence the electronic interactions between the donor and acceptor molecules, resulting in different photophysical properties. Our findings offer an improved understanding of the interplay between molecular packing and optoelectronic properties, providing a foundation for designing advanced materials for optoelectronic applications.

Crystal structure of acrinidinium tetrafluorohydrogenphthalate, C21H11F4NO4

C21H11F4NO4, triclinic, P 1 ‾ $P\overline{1}$ (no. 2), a = 9.5000(4) Å, b = 13.9989(7) Å, c = 14.1423(5) Å, α = 91.355(4)°, β = 108.542(4)°, γ = 98.958(4)°, V = 1756.02(14) Å3, Z = 4, R gt (F) = 0.0494, wR ref (F 2) = 0.1157, T = 293(2) K.

Synthesis and Properties of BN-embedded N-Perylene

A B-N embedded nitrogen-annulated perylene has been successfully synthesized. The resultant molecule BN-NP is isoelectronic to coronene , but owns a five-membered pyrrole ring. Experiments and DFT calculations indicated that peripheral pyrrole and BN modifications endow BN-NP with various unique properties like bent structure, dual emission, efficient Lewis acidic response, peripheral aromaticity, narrowest energy band gap among all coronene isoelectronic structures and so on.

Enhanced luminescence of single-benzene fluorescent molecules through halogen bond cocrystals

Organic single fluorescent molecules often suffer from aggregation-induced quenching effect under solid-state conditions, especially for red-emissive molecules, due to the flat rigid molecular framework and strong π-π interaction. Cocrystal engineering...

The competitive role of C–H⋯X (X = F, O) and π–π interactions in contributing to the degree of charge transfer in organic cocrystals: a case study of heteroatom-free donors with p-fluoranil (FA)

Four binary organic charge transfer cocrystals were grown by the slow cooling method. The competitive role of C–H⋯X (X = F, O) and π–π interactions in contributing to the degree of charge transfer in the cocrystals was investigated.