The preparation of photoresponsive polymer nanowires comprising photochromic azobenzene (Azo) and π-conjugated fluorene (FO) units is reported. Well-defined and uniform nanowires of the copolymer (PFOAzo) were successfully fabricated by the single particle nanofabrication technique after optimizing the FO:Azo ratio and the development conditions. Azo units in the PFOAzo nanowires underwent reversible trans–cis–trans isomerization upon exposure to ultraviolet or visible light, leading to changes in the radius (between ca. 6 and 8 nm) and morphology (straight or wavy) of the nanowires. The oligo(alkylfluorene) units in the backbone are found to profit the crosslinking efficiency upon high-energy ion beam irradiation, and more importantly, provide sufficient flexibility to allow reversible photoswitching. This demonstration of the photoluminescence, semiconducting, and mechanical properties of the PFOAzo nanowires is an important advance in the evolution of electro-mechanical nanomaterials.

New donor–acceptor-type copolymers comprised of benzobisthiazole (BBTz) as a weak donor rather than acceptor are proposed. This approach can simultaneously lead to deepening the HOMO and LUMO of the polymers with moderate energy offset against fullerene derivatives in bulk heterojunction organic photovoltaics. As a proof-of-concept, BBTz-based random copolymers conjugated with typical electron acceptors: thienopyrroledione (TPD) and benzothiadiazole (BT) based on density functional theory calculations are synthesized. Laser-flash and Xe-flash time-resolved microwave conductivity (TRMC) evaluations of polymer:[6,6]-phenyl C₆₁ butyric acid methyl ester (PCBM) blends are conducted to screen the feasibility of the copolymers, leading to optimization of processing conditions for photovoltaic device application. According to the TMRC results, alternating BBTz-BT copolymers are designed, exhibiting extended photoabsorption up to ca. 750 nm, deep HOMO (–5.5 to –5.7 eV), good miscibility with PCBM, and inherent crystalline nature. Moreover, the maximized PCE of 3.8%, the top-class among BBTz-based polymers reported so far, is realized in an inverted cell using TiO_x and MoO_x as the buffer layers. This study opens up opportunities to create low-bandgap polymers with deep HOMO, and shows how the device-less TRMC evaluation is of help for decision-making on judicious molecular design.

The fusion of bowl-shaped π-conjugated corannulene units to anion-responsive π-conjugated dipyrrolyldiketone-boron complexes resulted in new molecular materials with a unique self-assembly capability. The bowl-fused receptor with aliphatic tails could form both supramolecular gels and mesophases through π-stacking interactions and also exhibited anion-responsive characteristics. The presence of the π-bowl unit not only afforded enhanced self-assembly capability both in solution and in the mesophases, as evidenced by gelation experiments and phase-transition profiles, but also enhanced intrinsic charge-carrier mobility.

We present herein the synthesis and properties of the largest hitherto unknown graphyne fragment, namely trigonally expanded tetrakis(dehydrobenzo[12]annulene)s (tetrakis-DBAs). Intramolecular three-fold alkyne metathesis reactions of hexakis(arylethynyl)DBAs 9 a and 9 b using Fürstner’s Mo catalyst furnished tetrakis-DBAs 8 a and 8 b substituted with tert-butyl or branched alkyl ester groups in moderate and fair yields, respectively, demonstrating that the metathesis reaction of this protocol is a powerful tool for the construction of graphyne fragment backbones. For comparison, hexakis(arylethynyl)DBAs 9 c–g have also been prepared. The one-photon absorption spectrum of tetrakis-DBA 8 a bearing tert-butyl groups revealed a remarkable bathochromic shift of the absorption cut-off (λ_cutoff) compared with those of previously reported graphyne fragments due to extended π-conjugation. Moreover, in the two-photon absorption spectrum, 8 a showed a large cross-section for a pure hydrocarbon because of the planar para-phenylene-ethynylene conjugation pathways. Hexakis(arylethynyl)-DBAs 9 c–e and 9 g and tetrakis-DBA 8 b bearing electron-withdrawing groups aggregated in chloroform solutions. Comparison between the free energies of 9 e and 8 b bearing the same substituents revealed the more favorable association of the latter due to stronger π–π interactions between the extended π-cores. Polarized optical microscopy observations, DSC, and XRD measurements showed that 8 b and 9 e with branched alkyl ester groups displayed columnar rectangular mesophases. By the time-resolved microwave conductivity method, the columnar rectangular phase of 8 b was shown to exhibit a moderate charge-carrier mobility of 0.12 cm² V⁻¹ s⁻¹. These results indicate that large graphyne fragments can serve as good organic semiconductors.

Polygon-like [2+2]- and [3+3]-type metal complexes were prepared from dipyrrin dimers connected by acute-angled spacers. The electrical conduction depends strongly on the packing alignment of the compounds, revealing the presence of effective hopping pathways for holes with relatively high mobility up to 0.11 cm² V⁻¹ s⁻¹ along the aligned axis of [3+3]-type metal-bridged assemblies. These observations correlated with the geometrical control of the π-conjugated metal complexes in the cyclic structures, which enables their ordered arrangement in the assemblies.

In this paper a simple, casting solution technique for the preparation of two-dimensional (2D) arrays of very-high molecular weight (MW) 1D-Pc supramolecular inorganic polymers is described. The soluble fluoroaluminium tetra-tert-butylphthalocyanine (ttbPcAlF) is synthesized and characterized, which can be self-assembled to form 2D arrays of very-high-MW 1D-Pc supramolecular inorganic polymers. High-resolution transmission electron microscopy (HRTEM) demonstrates that the 1D-ttbPcAlF, having a cofacial ring spacing of ∼0.36 nm and an interchain distance of ∼1.7 nm, self-assembles into 2D-nanosheets (∼140 nm in length, ∼20 nm in width, and equivalent to MW of 3.2 × 10⁵ g mol⁻¹). The film cast from a 1,2-dichloroethane (DCE) solution shows a minimum hole-mobility of ∼0.3 cm² V⁻¹ s⁻¹ at room temperature by flash-photolysis time-resolved microwave conductivity (TRMC) measurements and a fairly high dark dc-conductivity of ∼1 × 10⁻³ S cm⁻¹.

On the basis of the chemistry in solution, the solid-state structures and the corresponding electronic and optical properties of dipyrrolyldiketone boron complexes as π-conjugated acyclic anion receptors have been investigated. Solid-state assemblies of the receptors exhibit anion-dependent properties that are in sharp contrast to those in the solution state. Anion complexation, along with structural differences in the pyrrole subunits such as a benzo-fused pyrrole, plays an essential role not only in the formation of the assembled modes but also in determining electronic and optical properties, as well as the charge-carrier mobilities. In addition, by anion complexation, inclusion of the counter cations into the crystals has also been found to be one of the essential factors to determine the properties.