the group consisting of hydrogen halo oxo c 1 20 alkyl c 1 20 hydroxyalkyl c 1 20 thioalkyl c 1 20 alkylamino c 1 20 alkylaminoalkyl c 1 20 aminoalkyl c 1 20 anninoalkoxyalkenyl c 1 20 aminoalkoxyalkynyl c 1 20 dianninoalkyl c 1 20 triaminoalkyl c 1 20 tetraminoalkyl c 5 15 aminotrialkoxyamino c 1 20 alkylam ido c 1 20 alkylam idoalkyl c 1 20 amidoalkyl c 1 20 acetamidoalkyl c 1 20 alkenyl c 1 20 alkynyl c 3 8 alkoxyl c 1 11 alkoxyalkyl and c 1 20 dialkoxyalkyl r1 is optionally substituted with a member selected from the group consisting of n u2014 oh acylamino cyano e g nc u2014 cyanamido e g ncnh u2014 cyanato e g nco u2014 sulfo sulfonyl sulfinyl sulfhydryl mercapto sulfeno sulfanilyl sulfamyl sulfamino and phosphino phosphinyl phospho phosphono and u2014 nrarb wherein each of ra and rb may be the same or different and each is independently selected from the group consisting of hydrogen optionally substituted alkyl cycloalkyl alkenyl cycloalkenyl alkynyl aryl heteroaryl and heterocyclic group each r2 and r3 is optionally substituted with one or more members of the group consisting of hydroxyl methyl carboxyl furyl furfuryl biotinyl phenyl naphthyl amino group amido group carbamoyl group cyano e g nc u2014 cyanamido e g ncnh u2014 cyanato e g nco u2014 sulfo sulfonyl sulfinyl sulfhydryl mercapto sulfeno sulfanilyl sulfamyl sulfamino phosphino phosphinyl phospho phosphono n u2014 oh u2014 si ch3 3 a k a sime3 c 1 3 alkyl c 1 3 hydroxyalkyl c 1 3 thioalkyl c 1 3 alkylamino benzyldihydrocinnamoyl group benzoyldihydrocinnamido group heterocyclic group and carbocyclic group the heterocyclic group or carbocyclic group is optionally substituted with one or more members of the group.