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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. 

Abstract The forthcoming generation of materials, including artificial muscles, recyclable and healable systems, photochromic heterogeneous catalysts, or tailorable supercapacitors, relies on the fundamental concept of rapid switching between two or more discrete forms in the solid state. Herein, we report a breakthrough in the “speed limit” of photochromic molecules on the example of sterically-demanding spiropyran derivatives through their integration within solvent-free confined space, allowing for engineering of the photoresponsive moiety environment and tailoring their photoisomerization rates. The presented conceptual approach realized through construction of the spiropyran environment results in ~1000 times switching enhancement even in the solid state compared to its behavior in solution, setting a record in the field of photochromic compounds. Moreover, integration of two distinct photochromic moieties in the same framework provided access to a dynamic range of rates as well as complementary switching in the material’s optical profile, uncovering a previously inaccessible pathway for interstate rapid photoisomerization.