NOVELTY - Benzodioxepin-3-one compounds (I) are new.    USE - (I) are useful: for protecting skin and hair against photoaging by light; as a fluorescent emitter in an electronic device comprising organic electroluminescent devices, organic integrated circuits, organic field-effect transistors, organic thin-film transistors, organic light-emitting transistors, organic solar cells, organic optical detectors, organic photoreceptors, organic field-quench devices, light emitting electrochemical cells and organic laser diodes; and as dyes (all claimed) for dyeing keratin fibers; and in organic light-emitting electrochemical cells.    ADVANTAGE - (I) have improved dyeing properties and high light, heat, pH, and oxidation stability, and are compatible with skin.    DETAILED DESCRIPTION - Benzodioxepin-3-one compounds of formula (I) and their salts, tautomers, stereoisomers, including their mixtures in all ratios and/or their solvates, are new.    R1-R4 = H, NO2, Hal, linear or branched 1-20C-alkyl or linear or branched 1-20C-alkoxy, where R1, R3 and R4 are preferably H;    X, Y1 = 5-24 membered (hetero)aryl (optionally one or more times substituted by R), where the aryl and/or heteroaryl groups are linked one or more times by a single bond, a double bond, conjugated double bonds, a carbon atom or a (CHR5)n-(Het)o-(CHR5)p;    R = D, Hal, alkyl, OH, O-alkyl, O-aryl, S-alkyl, NH2, NH-alkyl, N(alkyl)2, N(aryl)2, cycloalkyl, O-cycloalkyl, S-cycloalkyl, NH-cycloalkyl, N(cycloalkyl)2, CN, NO2, Si(alkyl)3, B(OR6)2, C(O)R6, P(O)(R6)2, S(O)R6, S(O)2R6, linear or branched 2-20C-alkenyl having one or more double bonds, or linear or branched 2-20C-alkynyl having at least one triple bond and optionally one or more double bonds;    R5 = H or R;    R6 = H, D, OH, alkyl, aryl, cycloalkyl, O-alkyl, O-aryl or O-cycloalkyl, where each alkyl is linear or branched 1-20C-alkyl (optionally partially substituted by halo), each cycloalkyl is an optionally partially unsaturated 3-7C-cycloalkyl, and each aryl is 6-10C-aryl (optionally substituted by one or more alkyl, O-alkyl, N(alkyl)2 or Hal);    Hal = F, Cl, Br or I;    Het = O, S, -N=N-, NH or NR;    n, p = 0-5; and    o = 0 or 1, where n+o+p is at least 1.    INDEPENDENT CLAIMS are included for:    (1) the preparation of (I);    (2) conjugated, partially conjugated, or non-conjugated polymers, oligomers or dendrimers, containing one or more (I);    (3) a preparation comprising (I); and    (4) preparing the preparation comprising mixing, preferably dispersing, emulsifying and dissolving (I) with at least one carrier and optionally additives and/or fillers.