A compound of the formula: ** Formula ** in which (a) each of Z1, Z2 and Z3 is N； (b) Xa, Xb and Xc are all carbon, connected by two single bonds or a single link and a double link； (c) Y is -CH2- or -S-； (d) X4 is hydrogen or halogen； and (e) X2 and R in combination are selected from the group consisting of: (i) X2 is halogen and R is primary amino-alkyl, a secondary or tertiary alkyl-amino-alkyl, in which the amine nitrogen it is substituted to satisfy valence, with the proviso that R is not a piperidine residue； and (ii) X2 is selected from the group consisting of alkyl, alkenyl, alkynyl, aryl, cycloalkyl, cycloalkenyl, saturated or unsaturated heterocycle, aryl, aryloxy, alkoxy, halogenated alkoxy, alkenyloxy, hydroxyalkyl, amino, alkylamino, dialkylamino, acylamino , carbamyl, amido, dialkylamido, alkylamido, alkylsulfonamido, sulfonamido, trihalocarbon, -thioalkyl, SO2-alkyl, -COO-alkyl, OH or alkyl-CN, or part of a ring formed by R, and R is (a) hydrogen； or (b) C1 to C10 straight or branched chain alkyl, C2 to C6 alkenyl or C2 to C6 alkynyl, which is unsubstituted or substituted； or (c) aryl, heteroaryl, heterocyclic, cycloalkyl, alkylaryl or arylalkyl, which is unsubstituted or substituted； or (d) -SR71, -S (O) R71, -SO2R71, -OR71, -COOR71, -CONR71R72, -CN, -R7AOR7B, -R7ANR7B, -R7ANR71R7B, -R7ASR7B, - R7AS (O) R7B, -R7ASO2R7B7B7R7B , -NR71R72, -OSO2N (R7c) 2, -N (R7c) SO2OH, -N (R7c) SO2R7c, -R7AOSO2N (R7C) 2 or - R7AN (R7C) OSO2R7C, where each R71 and R72 is independently selected from group consisting of hydrogen, COOR7B, CON (R7C) 2, C1 to C6 alkyl, C2 to C6 alkenyl, C2 to C6 alkynyl, -R7AOR7B, -R7ANR7B, -R7ASR7B, - R7AS (O) R7B, -R7ASO2R7B, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, alkylaryl, arylalkyl, alkylheteroaryl and heteroarylalkyl, each R7A is independently C1 to C6 alkyl, C2 to C6 alkenyl, C2 to C6 alkynyl, cycloalkyl, heterocycloalkyl, aryl, heteroaryl, alkylaryl or each alkyl is independently hydrogen, C1 to C6 alkyl, C2 to C6 alkenyl,
