Two　isomeric　star-shaped　dyes　(M1,　M2)　with　tetraphenylethylene　arms　and　distinct　cores　(β-enaminone　vs.　trimesoylamine)　were　synthesized　via　a　liquid-assisted　grinding　mechanochemical　approach.　M1　was　formed　by　Schiff　base　condensation,　while　M2　was　obtained　through　amidation.　The　core　structures　profoundly　influenced　their　optoelectronic　properties.　M2　exhibited　a　blueshifted　absorption　band　and　a　larger　optical　bandgap　relative　to　M1.　Critically,　M1　showed　aggregation-caused　quenching　(ACQ),　while　M2　displayed　aggregation-induced　emission　(AIE),　a　reversal　directly　driven　by　core　isomerization.　Both　isomers　responded　to　external　stimuli,　with　M2　exhibiting　exceptional　Fe3+　sensing　capability　in　aqueous　media　(THF/H2O　=　1:99,　v/v),　achieving　a　detection　limit　of　0.056　μM　and　demonstrating　1.8-fold　higher　sensitivity　than　M1.　Solid-state　M2　further　demonstrated　reversible　mechanochromism,　which　was　not　observed　in　M1.　These　minor　structural　differences　in　core　topology　drive　drastic　photophysical　changes,　which　establish　a　design　strategy　for　stimuli-responsive　fluorescent　dyes.　©　2025