SBF derivatives, represented with the following formula: SBF-X wherein: with m=0, 1, 2 or 3; p=positive integer,; n=positive integer; L: is the same or different and independently represents C, PR, AsR, SbR, BiR, S, Se, Te, S═Y, Se═Y or Te═Y; Y: is the same or different and independently represents O, S, Se or Te; K: is the same or different and independently represents a chemical bond or a group selected from O, S, BR(2−p), N, NR(2−p), R(2−p)P═O, B3O3, (PR)3N3, CR(3−p), CR(3−p)(C6H4)(p+1), SiR(3−p)(C6H4)(p+1) alkyne, substituted alkyne, alkyne, substituted alkyne, aromatic or R substituted aromatic, heteroaromatic-or a combination of two, three or four of the above mentioned groups; SBF: spiro-compound of formula (I): R, A, B, C, D: is the same or different and independently represents H, deuterium, F, Cl, Br, I, CN, a linear, branched or cyclic alkyl, alkoxy or thioalkoxy chain, or a combination from two, three or four of these systems; two or more substituents R can form a further monocyclic or polycyclic aliphatic or aromatic ring system with each other.