Use of a chemical sensor comprising, as sensitive material, at least one polymer comprising at least one repeat unit corresponding to the general formula below: in which: A 1, A 2 and A 3 represent, independently of one another, a substituted or unsubstituted phenyl or thienyl group; and B represents a substituted or unsubstituted chiral group of C2 symmetry or else a group corresponding to one of the formulae (a), (b) and (c) below: where: X represents a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; R 1 and R 2 represent, independently of one another: • a hydrogen or halogen atom; • a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; or still • a chemical functional group comprising at least one heteroatom; in the detection or assaying of one or more nitro compounds. A 1, A 2 and A 3 represent, independently of one another, a substituted or unsubstituted phenyl or thienyl group; and B represents a substituted or unsubstituted chiral group of C2 symmetry or else a group corresponding to one of the formulae (a), (b) and (c) below: where: X represents a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; R 1 and R 2 represent, independently of one another: • a hydrogen or halogen atom; • a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; or still • a chemical functional group comprising at least one heteroatom; X represents a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; R 1 and R 2 represent, independently of one another: • a hydrogen or halogen atom; • a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; or still • a chemical functional group comprising at least one heteroatom; • a hydrogen or halogen atom; • a saturated or unsaturated, linear, branched or cyclic, hydrocarbon group comprising from 1 to 100 carbon atoms, which hydrocarbon group can comprise one or more heteroatoms and/or one or more chemical functional groups comprising at least one heteroatom, and can be a substituted or unsubstituted aromatic or heteroaromatic group or can comprise one or more substituted or unsubstituted aromatic or heteroaromatic groups; or still • a chemical functional group comprising at least one heteroatom;