NOVELTY - (1,3)-Dioxan-5-one compounds (I) are new.    USE - (I) are useful: as dyes; and as fluorescent emitter in an electronic device comprising an organic electroluminescent device, an organic integrated circuit, an organic field-effect transistor, an organic thin film transistor, an organic light-emitting transistor, an organic solar cell, an organic optical detector, an organic photoreceptor, an organic field-quench device, a light-emitting electrochemical cell or an organic laser diode (all claimed). (I) are useful for dyeing matrices, such as skin, hair, nails or textiles. (I) are useful for treating e.g. psoriasis, acne, cellulite, skin wrinkling, skin aging, jaundice, vitiligo, inflammatory diseases, rheumatoid arthritis, pain, wounds, neurological diseases, edema, Paget's disease, primary and metastatic tumors, connective tissue diseases, viral diseases caused by herpes simplex or human papillomavirus and warts. No biological data given.    ADVANTAGE - (I) have improved skin compatibility and high light, heat, pH and oxidation stability, and improved dyeing properties.    DETAILED DESCRIPTION - (1,3)-Dioxan-5-one compounds of formula (I) and their salts, tautomers, stereoisomers, including their mixtures in all ratios and/or their solvates, are new.    R, R1=linear or branched 1-20C-alkyl;    X, Y1=5-24 membered (hetero)aryl group (optionally mono or polysubstituted by R2), where the (hetero)aryl groups are optionally linked one or more times by a single bond, double bond, conjugated double bond, a C-atom or by a unit of formula (CHR4) n-(Het) o-(CHR4) p;    R2=D, Hal, Alkyl, OH, O-Alkyl, O-aryl, S-Alkyl, NH 2, NH-Alkyl, N(Alkyl) 2, N(Aryl) 2, Cycloalkyl, O-Cycloalkyl, S-Cycloalkyl, NH-Cycloalkyl, N(Cycloalkyl) 2, CN, NO 2, Si(Alkyl) 3, B(OR3) 2, C(O)R3, P(O)(R3) 2, S(O)R3, S(O) 2R3, a linear or branched 2-20C-alkenyl having one or more double bonds or linear or branched 2-20C-alkynyl having at least one triple bonds and optionally one or more double bonds;    R3=H, D, OH, Alkyl, Aryl, Cycloalkyl, O-Alkyl, O-Aryl or O-Cycloalkyl;    R4=H, D, Hal, Alkyl, OH, O-Alkyl, O-Aryl, S-Alkyl, NH 2, NH-Alkyl, N(Alkyl) 2, N(Aryl) 2, Cycloalkyl, O-Cycloalkyl, S-Cycloalkyl, NH-Cycloalkyl, N(Cycloalkyl) 2, CN, NO 2, Si(Alkyl) 3, B(OR3) 2, C(O)R3, C(O) 2R3, P(O)(R3) 2, S(O)R3, S(O) 2R3, a linear or branched 2-20C-alkenyl having one or more double bonds or linear or branched 2-20C-alkynyl having at least one triple bonds and optionally one or more double bonds;    Alkyl=linear or branched 1-20C-alkyl (optionally partially or completely substituted by halo);    Cycloalkyl=optionally partially unsaturated 3-7C-cycloalkyl;    Aryl=6-10C-aryl (optionally one or more times substituted by Alkyl, O-Alkyl, N(Alkyl) 2or Hal);    Hal=F, Cl, Br or I;    Het=O, S, -N=N-, NH or NR2;    n, p=0-5; and    o=0 or 1, where n+o+p is at least 1.    Provided that (I) exclude 2-methoxy-4-(4-methoxy-benzylidene)-6-(1-(4-methoxy-phenyl)-meth-(Z)-ylidene)-2-methyl-(1,3)dioxan-5-one.    INDEPENDENT CLAIMS are included for:    (1) the preparation of (I);    (2) conjugated, partially conjugated or non-conjugated polymers, oligomers or dendrimers comprising (I), where the point of attachment between the (I) and the polymer, oligomer, or dendrimer lies at the position of one or more radicals of R2 of (I);    (3) preparation comprising (I); and    (4) preparing the preparation, comprising mixing, preferably dispersing, emulsifying and/or dissolving (I) with a carrier suitable for cosmetic, pharmaceutical, dermatological preparations, or household products, and optionally excipients and/or fillers.