Abstract: A compound of the structure ##STR1## wherein R and R.sup.1 are each, independently, hydrogen, ##STR2## R.sup.2 and R.sup.3 are each, independently, hydrogen, alkyl, alkenyl, alkynyl, --CO.sub.2 R.sup.5, --COR.sup.5, --CN, --NO.sub.2, --SO.sub.2 R.sup.5, --SO.sub.3 R.sup.5, --OR.sup.5, --SR.sup.5, or Ar;R.sup.4 is hydrogen, alkyl, alkenyl, alkynyl, --CF.sub.3, --NR.sup.5 R.sup.6, --CO.sub.2 R.sup.5, --COR.sup.5, CONR.sup.5 R.sup.6, --NO.sub.2, halogen, --OR.sup.5, --SR.sup.5, --CN, --SO.sub.2 R.sup.5, --SO.sub.3 R.sup.5, --SO.sub.2 NR.sup.5 R.sup.6 or Ar;R.sup.5 and R.sup.6 are each, independently, hydrogen, alkyl, alkenyl, alkynyl, or Ar; ##STR3## are each, independently, a 5-7 membered saturated, unsaturated, or partially unsaturated heterocyclic radical, that is optionally fused to a phenyl ring or a cycloalkane or cycloalkene ring, wherein the heterocyclic ring may optionally contain O, S, or NR.sup.8 in the heterocyclic ring, and may be optionally substituted by R.sup.7 ;R.sup.