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Achieving tunable electrical conductivity in organic materials is a key challenge for the development of next-generation semiconductors. This study demonstrates a novel approach using triphenylamine (TPA) bis-urea macrocycles as supramolecular hosts for guest-induced modulation of charge-transfer (CT) properties. By encapsulating guests with varying reduction potentials, including 2,5-dichloro-1,4-benzoquinone (ClBQ), 2,1,3-benzothiadiazole (BTD), and malononitrile (MN), we observed significant changes in the electrical conductivity. Crystals of the 1(ClBQ)0.31 complex exhibited an electrical conductivity of ∼2.08 × 10–5 S cm–1, a 10,000-fold enhancement compared to the pristine host. This is attributed to efficient CT observed in spectroscopic analyses and is consistent with the computed small HOMO–LUMO gap (2.92 eV) in a model of the host–guest system. 1(MN)0.39 and 1(BTD)0.5 demonstrated moderate conductivities explained by the interplay of electronic coupling, reorganization energy, and energy gap. Lower ratios of guest inclusion decreased the electrical conductivity by 10-fold in 1(ClBQ)0.18, while 1(MN)0.25 and 1(BTD)0.41 were nonconductive (10–9 S cm–1). This work highlights the potential of metal-free, porous organic systems as tunable semiconductors, offering a pathway to innovative applications in organic electronics. 

The structures and photoinduced radical (PIR) percentages of two crystalline solvates of unsubstituted triphenylamine bis-urea macrocycles are compared. Upon activation, both afford similar structures with higher PIR %. 

In this study, we combine experiments, calculated properties, and machine learning (ML) to design new triphenylamine-based (TPA) molecules that have a high photoinduced radical (PIR) generation in crystals. A dataset of 34 crystal structures was extracted from the Cambridge Crystallographic Data Centre. Eighteen structures with experimentally reported PIR values from 0 to 0.85% were used to build an ML model trained using Random Forest that achieves an average leave-one-out test set error of 0.173% PIR. The ML model was used to screen the remaining 16 compounds, of which 4 were selected and sub-sequently compared with the experimentally measured PIR%. The predicted PIR% demonstrated good agreement with the measured values of TPA bis-urea macrocycles host-guest complexes and non-macrocyclic compounds of TPAs. Examining a broad set of molecular architectures/scaffolds allows for investigating the structural and electronic properties that lead to high PIR generation. We found very different trends for macrocycles, linear TPAs, and mono TPAs, where mono TPAs consist-ently have the lowest PIR generation. Macrocycles tend to have the highest PIR generation, especially for systems with ben-zene and fluorobenzene guests. Although linear analogs overall perform worse than macrocycles, they display clear trends with increasing excited-state dipole moment, oscillator strength and electron-hole covariance, while decreasing ionization potential and interatomic distance are generally correlated with higher PIRs. What is consistently observed is that higher PIRs are seen for brominated analogs. Our study, therefore, provides guidelines for future design strategies of TPAs for PIR generation. 

Herein, we investigate supramolecular gelation behavior of a dendronized triphenylamine bis-urea macrocycle (1) in toluene in the presence and absence of sulfoxide chain stoppers. Macrocycle 1 assembles in the sol phase through intermolecular hy-drogen bonding interactions, spontaneously transitioning into a gel state when left undisturbed at room temperature. In tolu-ene, 1 displays a critical gelation concentration of 0.066 wt%, classifying it as a super-gelator. Furthermore, it exhibits a thermoreversible gel-sol phase transition as well as thixotropic behavior. Temperature-dependent 1H NMR spectroscopy is employed to probe the sol phase assembly of 1 with the size variations at different temperatures assessed by 2D DOSY. Rheological experiments at 10 °C were used to measure gelation response to mechanical stimuli. An amplitude sweep test highlights a linear viscoelastic region. Additionally, the self-healing behavior of gel 1 was verified through a series of strain cycles, where it showed complete recovery. Addition of chain stoppers 10% versus 1 of dimethyl sulfoxide (DMSO) and diphenyl sulfoxide (DPS) lead to weaker gels with smaller differences between the storage and the loss moduli. Rheological analysis revealed slower/partial recovery for the gel containing chain stoppers. Gels assembled from macrocyclic building blocks may retain homogeneous binding cavity and channels offering novel functional properties. 

Herein, we report structural, computational, and conductivity studies on urea-directed self-assembled iodinated triphenylamine (TPA) derivatives. Despite numerous reports of conductive TPAs, the challenges of correlating their solid-state assembly with charge transport properties hinder the efficient design of new materials. In this work, we compare the assembled structures of a methylene urea bridged dimer of di-iodo TPA (1) and the corresponding methylene urea di-iodo TPA monomer (2) with a di-iodo mono aldehyde (3) control. These modifications lead to needle shaped crystals for 1 and 2 that are organized by urea hydrogen bonding, π⋯π stacking, I⋯I, and I⋯π interactions as determined by SC-XRD, Hirshfeld surface analysis, and X-ray photoelectron spectroscopy (XPS). The long needle shaped crystals were robust enough to measure the conductivity by two contact probe methods with 2 exhibiting higher conductivity values (∼6 × 10 −7 S cm −1 ) compared to 1 (1.6 × 10 −8 S cm −1 ). Upon UV-irradiation, 1 formed low quantities of persistent radicals with the simple methylurea 2 displaying less radical formation. The electronic properties of 1 were further investigated using valence band XPS, which revealed a significant shift in the valence band upon UV irradiation (0.5–1.9 eV), indicating the potential of these materials as dopant free p-type hole transporters. The electronic structure calculations suggest that the close packing of TPA promotes their electronic coupling and allows effective charge carrier transport. Our results show that ionic additives significantly improve the conductivity up to ∼2.0 × 10 −6 S cm −1 in thin films, enabling their implementation in functional devices such as perovskite or solid-state dye sensitized solar cells.