Five new, constrained, aryl-substituted 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) dyes (3f, g and 4h-j) were prepared and investigated to see if they have more favorable fluorescence characteristics than the unconstrained systems 2 that were prepared in previous studies. Dye types 3 and 4 have relatively rigid conformations caused by the heteroatom (3f and 3g) or ethylene bridge (4h-j) linkers that preclude free rotation of the ...