Indolonaphthopyrans
Provided is a photochromic indolenaphthopyran compound having the skeletal structure of Formula (I): wherein R 1 and R 2 each independently have a steric bulk A, wherein at least one of R 1 or R 2 has a steric bulk A of at least 0.6, R 3 and R 4 each independently have a Hammett σp value, and wherein the indolenaphthopyran compound has a calculated electronic steric factor of at least −3.3.
1. An indolenaphthopyran compound represented by Formula (I),
wherein,
R 1 and R 2 each independently have a steric A value,
wherein at least one of R 1 or R 2 has a steric A value of at least 0.6, and at least one of R 1 and R 2 is, in each case independently, alkyl, alkoxy, or perfluoroalkyl,
R 3 and R 4 each independently have a Hammett 6p value, wherein at least one of R 3 and R 4 is, in each case independently, hydrogen, alkyl, acyclic alkyl amine, alkoxy, fluoro, or a nitrogen-containing heterocycle selected from morpholino, piperidino, and pyrrolidino,
wherein the indolenaphthopyran compound has a calculated electronic steric factor of at least −3.3, wherein the electronic steric factor (ESF) is calculated in accordance with the following equation,
ESF=[(sum of Hammett σ p values for R 3 and R 4 ))×10]+(sum of steric A values for R 1 and R 2 )
m is 0 to 4, n is 0 to 4; and
R 5 independently for each m and R 6 independently for each n are:
alkyl;
a perfluoroalkyl group; or
alkoxy.
2. The indolenaphthopyran compound of claim 1 , wherein the indolenaphthopyran compound has a calculated electronic steric factor of at least 0.
3. The indolenaphthopyran compound of claim 1 , wherein at least one of R 1 or R 2 is methyl, ethyl, butyl, tert-butyl, trifluoromethyl, or methoxy.
4. The indolenaphthopyran compound of claim 1 , wherein both R 1 and R 2 are the same group.
5. The indolenaphthopyran compound of claim 1 , wherein at least one of R 3 or R 4 is methoxy, fluoro, or morpholino.
6. The indolenaphthopyran compound of claim 1 , represented by Formula (Ib):
wherein R 7 is selected from the group consisting of alkyl, alkoxy, haloalkyl, and a nitrogen-containing heterocycle selected from morpholino, piperidino, and pyrrolidino.
7. The indolenaphthopyran compound of claim 1 , wherein R 1 is trifluoromethyl, R 2 is trifluoromethyl or hydrogen, R 3 is hydrogen, and R 4 is hydrogen.
8. A photochromic composition comprising the indolenaphthopyran compound of claim 1 .
9. A photochromic article comprising the indolenaphthopyran compound of claim 1 , wherein the photochromic article is selected from ophthalmic articles, display articles, windows, mirrors, active liquid crystal cell articles, or passive liquid crystal cell articles.
10. The photochromic article of claim 9 , wherein the photochromic article is selected from ophthalmic articles, and the ophthalmic articles are selected from corrective lenses, non-corrective lenses, contact lenses, intra-ocular lenses, magnifying lenses, protective lenses, or visors.
11. The photochromic article of claim 9 , wherein the photochromic article is selected from display articles, and the display articles are selected from screens, monitors, or security elements.