TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation of poly-trifluoroborate compound (I) comprises reacting polyboronic acid of formula (R)x-A-(B(OH)2)n with potassium hydrogen fluoride in aqueous medium. Preferred Components:The polyboronic acid is used in methanolic solution. Preferred Definitions:    A = 1,4-phenylene, 2,5-thienyl or 2,5-pyridinyl (all optionally substituted with 4 residues, preferably H, 1-24C alkyl or alkoxy) or at least two aromatic, heteroaromatic or aromatic and heteroaromatic rings or condensed ring system, where the two rings are connected to each other with an exocyclic bond e.g. in 4,4'-biphenylene, 2,2'-bithienylene, 4,4'-binaphthyl, 4,10'-(9-phenyl-anthracene)ylene or at least two aromatic, heteroaromatic or aromatic and heteroaromatic rings or condensed ring system, where the two rings are connected to each other over a group G or at least two aromatic, heteroaromatic or aromatic and heteroaromatic rings or condensed ring system, where the two rings are connected to each other over a bond and a group G1;    G = O, S, N, P, Si, CO, SO, SO2, NR, CO2, ethenylene, ethynylene, buta-1,3-diene-1,4-ylene, 1,4-phenylene, 4,4'-biphenylene, 2,5-thienylene, 9,10-anthracenylene or complex units e.g. N,N,N-triphenylamine-4,4'-ylene or N,N,N',N'-tetraphenylbenzidin-4'',4''''-ylene;    G1 = O, S, N, P, Si, CO, SO, SO2, NR, CO2, vinyl-1,2-ene, methylene CR2;    x+n = 2-4;    R = BF3X; and    X = potassium ion or tetra-n-butylammonium ion    SPECIFIC COMPOUNDS - 208 Compounds (I) are specifically claimed e.g. potassium(4,4'-(ethyne-1,2-diyl)bis(4,1-phenylene)bis(trifluoroborate), potassium 1,4 phenylene bis(trifluoroborate), potassium biphenyl-4,4'-diylbis(trifluoroborate), potassium(9,9-dimethyl-9H-fluorene-2,7-diyl)bis(trifluoroborate) and potassium(10-phenyl-10H-phenoxazine-2,8-diyl)bis(trifluoroborate).    EXAMPLE - A solution of stillbene-4,4'-diboronic acid (2 g) and potassium hydrogen fluoride (4.6 g) were refluxed in 140 ml water for 2 hours. Then the mixture was cooled to room temperature and the obtained solid was filtered, washed with water (20 ml) and methanol (20 ml) and then dried under vacuum to obtain dipotassiumstillbene-4,4'-bistrifluoroborate (2.8 g) with 96% theoretical yield.