A Porous Polymer of Thienothiophene and Tetraphenylethylene: Design, Synthesis and Photophysical Properties

A novel conjugated porous polymer (CPP) based on thieno[3,2-b]thiophene (TT) and tetraphenylethylene (TPE) was successfully designed and synthesized via a Pd(0)-catalyzed Suzuki cross-coupling reaction. Owing to its rigid, highly cross-linked architecture, the resulting TT–TPE polymer is insoluble and exhibits permanent porosity. Comprehensive characterization using UV–Vis, fluorescence, and FTIR spectroscopy, together with scanning electron microscopy (SEM), cyclic voltammetry (CV), and thermogravimetric analysis (TGA), confirmed the successful formation of a robust π-conjugated porous network. The polymer exhibits a strong π–π* absorption band at 392 nm, intense fluorescence emission at 549 nm, and a large Stokes shift, indicating efficient intramolecular energy transfer and significant excited-state relaxation. SEM images reveal a hierarchically porous, sponge-like morphology, while electrochemical studies demonstrate stable redox behavior and favorable HOMO and LUMO energy levels, highlighting its potential for optoelectronic applications. Furthermore, the optical and electrochemical band gaps are in good agreement, indicating the reliability of the experimental results. Density functional theory (DFT) calculations further corroborate the experimental findings, showing excellent agreement between the simulated and observed electronic transitions. Overall, the TT–TPE conjugated porous polymer represents a promising functional material for applications in chemical sensing, energy storage, and optoelectronic devices.