Naphthopyran compounds, photoresponsive compositions and lenses

A photochromic [1,2-b] naphthopyran having a fluoro substituent in at least one of the 7-position or the 9-position of the naphthopyran provides a stable photochromic compound with a narrow range of absorption. A preferred photochromic naphthopyran has the 2-position of the naphthopyran with two aromatic substituents thereon. It is further preferred to have at least one 2-position aromatic substituent comprising a phenyl group. The photochromic naphthopyran may also have at least one 2-position aromatic substituent comprise a phenyl group having one substituent selected from the group consisting of an anthranilyl, azepinyl, benzoxazolyl, dialkylamino, diazepinyl, diazolyl, imidazolidinyl, imidazolyl, imidazolinyl, indazolyl, indo eninyl, indolinyl, indolizinyl, indolyl, indoxazinyl, isobenzazolyl, isoindolyl, isooxazolyl, isooxazyl, isopyrrol, isoquinolyl, isothiazolyl, julolideno, morpholino, morpholinyl, oxadiazolyl, oxathiazolyl, oxathiazyl, oxathiolyl, oxatriazolyl, oxazolyl, piperazinyl, piperazyl, piperidyl, purinyl, pyranopyrrolyl, pyrazinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, pyrazyl, pyridazinyl, pyridazyl, pyridyl, pyrimidinyl, pyrimidyl, pyridenyl, pyrrolidinyl, pyrrolinyl, pyrroyl, quinolizinyl, quinocyclidinyl, quinolyl, thiazolyl, triazolyl and triazyl group.