In this paper, new thieno[2,3-d]pyrimidine analogs have been synthesized and characterized through different spectroscopic techniques. The photophysical properties of the molecules (7b-7f) and the quantum chemical calculations have been investigated. These molecules exhibited aggregation-induced emission behavior and showed efficient emission in both solid and solution states. A shift toward shorter wavelengths (hypsochromic shift) was observed when transitioning from the solution to the solid state, which could be explained by photoinduced intramolecular charge transfer (ICT) processes. DFT calculations confirmed that the diverse behavior of the thieno[2,3-d]pyrimidine analogs could be attributed to variations in molecular packing and rigidity. This study illustrates how luminophores aggregation can occur without significantly impacting the excited state, emphasizing the unconventional behavior …