Patent ID: 8193174

Claim:
A compound comprising a xanthone or thiaxanthone sensitizing moiety having an integral pyridyl group that constitutes part of the moiety, the integral pyridyl group having a nitrogen atom capable of coordinating to a lanthanide ion, wherein the compound has any one of the following formulae 1 and 2: wherein: R 1 is H, alkyl, aralkyl, CO 2 R 3 , or CONHR 3 ; R 2 is H, alkyl or aralkyl; R 3 is alkyl, aralkyl or aryl, optionally substituted; R 4 is H, alkyl, aralkyl, or CO 2 R 6 ; R 5 is CH 2 CH 2 NHSO 2 R 6 ; R 6 is alkyl, p-R 4 -Ph, p-OMe-Ph, or p-CF 3 -Ph; X is O or S; Y is the nitrogen atom capable of coordinating and binding to the lanthanide ion; Z 1 is CO 2 − , PR 1 O 2 − , PO 3 2− , or CONHR 3 ; and Z 2 is CO 2 − , PR 4 O 2 − , PO 3 2− , or CONHR 4 .