The development of planar luminogens with an isoelectronic B–N moiety and replacing the conventional CC bonds is an unusual approach to tune the optical properties of organic materials in solution and the condensed phase. Herein, three boron congeners and their analogous carbon congeners are developed via engineering the aliphatic/aromatic functionality, unveiling the role of each functionality in intermolecular packing and luminogenic behavior. The boron-fused molecules exhibited slip-stack packing orientation governed by B–π interactions and showed aggregation induced emission in the condensed state unlike the carbon analogs which had a typical aggregation caused quenching (ACQ) phenomenon. Notably, the offset dimeric arrangement in the octyl chain substituted boron congener offers highly emissive nano-assemblies and solid-state luminescence, which was utilized for fluorescence-based rapid detection of broadly used tetracycline and oxytetracycline antibiotics. This detection was further translated into a prototype technique using a smartphone-based platform for easy, onsite detection. Examining the structure–property relationship could lead to the development of highly emissive unusual luminogens by restricting the detrimental π–π stacking via insertion of a BN moiety into the cyclic hydrocarbon framework. This promising strategy provides access to potential planar luminogens while generating unusual photophysical properties for advanced applications.