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Two diastereoisomers (NTPH-P and NTPH-T1) as a C 2-symmetric triple [5]helicene based on N -annulated triperylene hexaimide were synthesized. Aided by nuclear magnetic resonance spectroscopy (NMR) and theoretical calculations, NTPH-P was assigned to three-blade propeller conformation while NTPH-T1 tended to exhibit twisted conformation with pyrrole ring fusing on a bowl-shaped PDI foil. Characterized by circular dichroism (CD) and circular polarized luminescence (CPL) measurements, the enantiomerically pure NTPH-P exhibited fairly good chiral activities both in the absorption and emission range with dissymmetry factors | g abs| of 4.1×10−3 and | g lum| of 1.2×10−3. The diastereoisomers were further employed as acceptors for organic solar cells with distinct PCEs of 8.11% and 5.24% for NTPH-P and NTPH-T1 based devices, respectively, signifying the prospects in chiroptical electronics by designing molecularly defined aromatics.

The possibility and rate of charge separation (CS) in donor-bridge-acceptor molecules mainly depend on two factors: electronic coupling and solvent effects. The question of how CS occurred in two identical chromophores is fundamental, as it is particularly interesting for potential molecular electronics applications and the photosynthetic reaction centers (RCs). Conjugated bridge definitely plays a crucial role in electronic coupling. To determine the bridge-mediated charge separation dynamics between the two identical chromophores, the isomeric N-annulated perylene diimide dimers (para-BDNP and meta-BDNP) with different conjugated bridge structures have been comparatively investigated in different solvents using femtosecond transient absorption spectra (fs-TA). It is found that the charge separation is disfavored in weak polar solvent, whereas direct spectroscopic signatures of radicals are observed in polar solvents, and the rate of charge separation increases as the solvent polarity increasing. To our surprise, the rate of charge separation in m-BDNP is more than an order of magnitude slower than that in p-BDNP, although there is a larger negative ΔGCS in m-BDNP. The slow CS rate that occurred in m-BDNP mainly results from the intrinsic destructive interference of the wave function through the meta-substituted bridge. The roles of solvent effects in free energy and electronic coupling for charge separation are further identified with quantum calculations.

The first example of sila-annulation onto the perylene diimide core that allows the effective and practical synthesis of both sila- and disilaperylene diimides (Si-PDIs and 2Si-PDIs) in one pot through palladium-catalyzed Si–C bond formation is presented. The corresponding sila-annulated perylene diimides demonstrated exceptional optical properties with noteworthy bathochromic shifts and excellent fluorescence quantum yields. Single crystal analysis revealed almost planar molecular structures and distinct packing arrangements with intense π–π interactions. Their single crystal OFET devices showed good electron mobilities of up to 0.3 cm2 V–1 s–1 under a nitrogen atmosphere.