A compound of formula, or a hydrate or a solvate thereof: wherein Ar, and Ar 2 may be identical or different and are each independently selected from the group consisting of groups of formula and: R a is C 1 -C 6 alkyl, optionally substituted with a OH group, a O-(C 1 -C 4)alkyl group or a monocyclic or bicyclic 5- to 10-membered aromatic or heteroaromatic group, R b is a hydrogen atom, a halogen atom, C 1 -C 6 alkyl optionally substituted with a OH group, or a O-(C 1 -C 4)alkyl group, Y 1 and Z 1 are independently CH or N + -R c, provided that al least one of Y 1 and Z 1 is N + -R c + and at least one of Y 1 and Z 1 is CH, R c is C 1 -C 6 alkyl, optionally substituted with a OH group, a O-(C 1 -C 4)alkyl group, or a monocyclic or bicyclic 5- to 10-membered aromatic or heteroaromatic group, X 2- is one or a plurality of pharmaceutically acceptable anion(s), selected so as to obtain an overall electrically neutral salt, L is, or: provided that Ar 1 and Ar 2 are not groups of formula when L is or, m, n, p, u and v may be identical or different and are each independently an integer selected from 0 to 2; s is an integer selected from 0 to 3; R 1, R 2, R 3, R 6, R 8 and R 9 may be identical or different and are each independently a halogen atom, a C 1 -C 6 alkyl group, a C 3 -C 8 cycloalkyl group, a O(C 1 -C 6)alkyl group, a NR 10 R 11 group, a C 2 -C 6 alkenyl group, a C 5 -C 8 cycloalkenyl group said C 1 -C 6 alkyl group, C 3 -C 8 cycloalkyl group, O(C 1 -C 6)alkyl group, C 2 -C 6 alkenyl group, or C 5 -C 8 cycloalkenyl group being optionally substituted with one to three halogen atoms, a OH group, a O-(C 1 -C 6)alkyl group, a NH-(C 1 -C 6)alkyl group or a NHC -R'; R 10 and R 11 may be identical or different and are each independently: - a hydrogen atom, - a C 1 -C 6 alkyl group optionally substituted with a OH group, a O-(C 1 -C 6)alkyl group, a NH-(C 1 -C 6)alkyl group or a NHC -R', or NR 10 R 11, taken together, form a 3- to 8-membered heterocycloalkyl or 5- to 8-membered heterocycloalkenyl, R' is a (C 1 -C 6)alkyl group optionally substituted with a C 5 -C 10 aryl group, wherein said C 5 -C 10 aryl group is optionally substituted with a halogen atom, a C 1 -C 6 alkyl group, a O(C 1 -C 6)alkyl group, a C 2 -C 6 alkenyl group, a C 5 -C 8 cycloalkenyl group, a 3- to 8-membered heterocycloalkyl, a 5- to 8-membered heterocycloalkenyl, a N((C 1 -C 6)alkyl) 2 group or a N((C 1 -C 6)haloalkyl) 2 group. R a is C 1 -C 6 alkyl, optionally substituted with a OH group, a O-(C 1 -C 4)alkyl group or a monocyclic or bicyclic 5- to 10-membered aromatic or heteroaromatic group, R b is a hydrogen atom, a halogen atom, C 1 -C 6 alkyl optionally substituted with a OH group, or a O-(C 1 -C 4)alkyl group, Y 1 and Z 1 are independently CH or N + -R c, provided that al least one of Y 1 and Z 1 is N + -R c + and at least one of Y 1 and Z 1 is CH, R c is C 1 -C 6 alkyl, optionally substituted with a OH group, a O-(C 1 -C 4)alkyl group, or a monocyclic or bicyclic 5- to 10-membered aromatic or heteroaromatic group, X 2- is one or a plurality of pharmaceutically acceptable anion(s), selected so as to obtain an overall electrically neutral salt, L is, or: provided that Ar 1 and Ar 2 are not groups of formula when L is or, m, n, p, u and v may be identical or different and are each independently an integer selected from 0 to 2; s is an integer selected from 0 to 3; R 1, R 2, R 3, R 6, R 8 and R 9 may be identical or different and are each independently a halogen atom, a C 1 -C 6 alkyl group, a C 3 -C 8 cycloalkyl group, a O(C 1 -C 6)alkyl group, a NR 10 R 11 group, a C 2 -C 6 alkenyl group, a C 5 -C 8 cycloalkenyl group said C 1 -C 6 alkyl group, C 3 -C 8 cycloalkyl group, O(C 1 -C 6)alkyl group, C 2 -C 6 alkenyl group, or C 5 -C 8 cycloalkenyl group being optionally substituted with one to three halogen atoms, a OH group, a O-(C 1 -C 6)alkyl group, a NH-(C 1 -C 6)alkyl group or a NHC -R'; R 10 and R 11 may be identical or different and are each independently: - a hydrogen atom, - a C 1 -C 6 alkyl group optionally substituted with a OH group, a O-(C 1 -C 6)alkyl group, a NH-(C 1 -C 6)alkyl group or a NHC -R', - a hydrogen atom, - a C 1 -C 6 alkyl group optionally substituted with a OH group, a O-(C 1 -C 6)alkyl group, a NH-(C 1 -C 6)alkyl group or a NHC -R', or NR 10 R 11, taken together, form a 3- to 8-membered heterocycloalkyl or 5- to 8-membered heterocycloalkenyl, R' is a (C 1 -C 6)alkyl group optionally substituted with a C 5 -C 10 aryl group, wherein said C 5 -C 10 aryl group is optionally substituted with a halogen atom, a C 1 -C 6 alkyl group, a O(C 1 -C 6)alkyl group, a C 2 -C 6 alkenyl group, a C 5 -C 8 cycloalkenyl group, a 3- to 8-membered heterocycloalkyl, a 5- to 8-membered heterocycloalkenyl, a N((C 1 -C 6)alkyl) 2 group or a N((C 1 -C 6)haloalkyl) 2 group.