| US 7,556,751 B2 | ||
| Photochromic materials having electron-withdrawing substituents | ||
| Anu Chopra, Pittsburgh, Pa. (US); Beon-Kyu Kim, Gibsonia, Pa. (US); and Barry Van Gemert, Pitcairn, Pa. (US) | ||
| Assigned to Transitions Optical, Inc., Pinellas Park, Fla. (US) | ||
| Filed on Dec. 21, 2005, as Appl. No. 11/314,141. | ||
| Prior Publication US 2007/0138449 A1, Jun. 21, 2007 | ||
| This patent is subject to a terminal disclaimer. | ||
| Int. Cl. G02B 5/23 (2006.01) | ||
| U.S. Cl. 252—586 [549/352; 549/382; 544/149] | 25 Claims |
1. A photochromic material representable by the following structure III:
 R16 is a first electron withdrawing group having a Hammett σp value of from 0.05 to 0.75;
R17 is: hydrogen, or a second electron withdrawing group having a Hammett σp value of from 0.05 to 0.75;
q is the integer 0, and s is the integer 0;
R19 and R20 are each independently: hydrogen; C1-C6 alkyl; C3-C7 cycloalkyl; allyl; substituted or unsubstituted phenyl; substituted or unsubstituted benzyl; chloro; fluoro; the group —C(═O)W,
wherein W is hydrogen, hydroxy, C1-C6 alkyl, C1-C6 alkoxy, the unsubstituted, mono- or disubstituted aryl groups phenyl or naphthyl, phenoxy, mono- or di-(C1-C6)alkoxy substituted phenoxy, mono- or di-(C1-C6)alkoxy substituted phenoxy, amino, mono(C1-C6)alkylamino, di(C1-C6)alkylamino, phenylamino, mono- or di-(C1-C6)alkyl substituted phenylamino, or mono- or di-(C1-C6)alkoxy substituted phenylamino; or R19 and R20 together form a spiro-carbocyclic group containing 3 to 6 carbon atoms, or a spiro-heterocyclic group containing 1 to 2 oxygen
atoms and 3 to 6 carbon atoms including the spirocarbon atom, said spiro-carbocyclic and spiro-heterocyclic groups being annellated
with 0, 1 or 2 benzene rings, provided that substitution at the carbon to which R19 and R20 are attached does not comprise hydroxyl; and
B and B′ are each independently an unsubstituted, or substituted aryl group that has at least one pi-bond capable of being
in conjugation with the pi-system of the open form of the core indeno-fused naphthopyran structure, provided that substitution
at the 13-position of the indeno-fused naphthopyran does not comprise hydroxyl.
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