A compound of the formula wherein: Alk 1 is a branched or unbranched alkylene chain of 2 to 6 carbon atoms; Sp 1 is selected from -S-, -O-, -CONH-, -NHCO-, and -NR'-; Z 1 is H, or alkyl of 1 to 5 carbon atoms; Ar is 1,2-, 1,3-, or 1,4-phenylene optionally substituted with one, two, or three groups independently selected from alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 5 carbon atoms, thioalkoxy of 1 to 4 carbon atoms, halogen, nitro, -COOR', -CONHR', -O(CH 2) n COOR', - S(CH 2) n COOR', -O(CH 2) n CONHR', and -S(CH 2) n CONHR' or a 1,2-, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 1,8-, 2,3-, 2,6-, or 2,7-naphthylidene optionally substituted with one, two, three, or four groups independently selected from alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 5 carbon atoms, thioalkoxy of 1 to 4 carbon atoms, halogen, nitro, -COOR', -CONHR', - O(CH 2) n COOR', -S(CH 2) n COOR', -O(CH 2) n CONHR', and -S(CH 2) n CONHR'; n is an integer from 0 to 5; R' is a straight or branched alkyl of 1 to 5 carbon atoms optionally substituted by one or two groups of -OH, alkoxy of 1 to 4 carbon atoms, thioalkoxy of 1 to 4 carbon atoms; Sp is a straight or branched-chain divalent or trivalent alkyl radical of 1 to 18 carbon atoms, divalent or trivalent aryl or heteroaryl radical, divalent or trivalent cycloalkyl of 3 to 18 carbon atoms or heterocycloalkyl radical, divalent or trivalent aryl- or heteroaryl-alkyl (C 1 -C 18) radical, divalent or trivalent cycloalkyl- or heterocyclo-alkyl-alkyl (C 1 -C 18) radical or divalent or trivalent unsaturated alkyl radical of 2 to 18 carbon atoms, wherein heteroaryl is furyl, thienyl, N-methylpyrrolyl, pyridinyl, N-methylimidazolyl, oxazolyl, pyrimidinyl, quinolyl, isoquinolyl, N-methylcarbazoyl, aminocoumarinyl, or phenazinyl and wherein if Sp is a trivalent radical, it can be additionally substituted by dialkylamino of 1 to 5 carbon atoms, alkoxy of 1 to 5 carbon atoms, hydroxy, or alkylthio of 1 to 5 carbon atoms groups; Q is selected from the group consisting of -NNHCO-, -NNHCS-, and -NNHCONH-; Z is selected from the group consisting of Alk 1 is a branched or unbranched alkylene chain of 2 to 6 carbon atoms; Sp 1 is selected from -S-, -O-, -CONH-, -NHCO-, and -NR'-; Z 1 is H, or alkyl of 1 to 5 carbon atoms; Ar is 1,2-, 1,3-, or 1,4-phenylene optionally substituted with one, two, or three groups independently selected from alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 5 carbon atoms, thioalkoxy of 1 to 4 carbon atoms, halogen, nitro, -COOR', -CONHR', -O(CH 2) n COOR', - S(CH 2) n COOR', -O(CH 2) n CONHR', and -S(CH 2) n CONHR' or a 1,2-, 1,3-, 1,4-, 1,5-, 1,6-, 1,7-, 1,8-, 2,3-, 2,6-, or 2,7-naphthylidene optionally substituted with one, two, three, or four groups independently selected from alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 5 carbon atoms, thioalkoxy of 1 to 4 carbon atoms, halogen, nitro, -COOR', -CONHR', - O(CH 2) n COOR', -S(CH 2) n COOR', -O(CH 2) n CONHR', and -S(CH 2) n CONHR'; n is an integer from 0 to 5; R' is a straight or branched alkyl of 1 to 5 carbon atoms optionally substituted by one or two groups of -OH, alkoxy of 1 to 4 carbon atoms, thioalkoxy of 1 to 4 carbon atoms; Sp is a straight or branched-chain divalent or trivalent alkyl radical of 1 to 18 carbon atoms, divalent or trivalent aryl or heteroaryl radical, divalent or trivalent cycloalkyl of 3 to 18 carbon atoms or heterocycloalkyl radical, divalent or trivalent aryl- or heteroaryl-alkyl (C 1 -C 18) radical, divalent or trivalent cycloalkyl- or heterocyclo-alkyl-alkyl (C 1 -C 18) radical or divalent or trivalent unsaturated alkyl radical of 2 to 18 carbon atoms, wherein heteroaryl is furyl, thienyl, N-methylpyrrolyl, pyridinyl, N-methylimidazolyl, oxazolyl, pyrimidinyl, quinolyl, isoquinolyl, N-methylcarbazoyl, aminocoumarinyl, or phenazinyl and wherein if Sp is a trivalent radical, it can be additionally substituted by dialkylamino of 1 to 5 carbon atoms, alkoxy of 1 to 5 carbon atoms, hydroxy, or alkylthio of 1 to 5 carbon atoms groups; Q is selected from the group consisting of -NNHCO-, -NNHCS-, and -NNHCONH-; Z is selected from the group consisting of