TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The composition is crystalline. The second portion is comprised by a compound that is crystalline at room temperature. The first portion and the second portion are comprised by a single compound. The non-covalent interaction between the carbonyl oxygen and the halogen atom is via an intramolecular directed heavy atom effect. Preferred Composition: The composition further comprises a polymer; and at least two molecules of the compound. Preferred Method: In the method, the distance between the oxygen of the carbonyl group and the halogen atom is maintained at less than the vander Waals radii of the oxygen of the carbonyl group and the halogen atom by crystallizing at least a portion of the composition, entangling the composition with a polymer, or providing the first portion and the second portion in a single compound so that the non-covalent interaction between the carbonyl oxygen and the halogen atom is via an intramolecular directed heavy atom effect.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Compound: The compound is of formula R3-R1(X)(OR2)-R4 (I), R6-R5(X)2-R7 (II) and R9-R8(X)(OR2)-R10 (III).R1 and R5=aromatic group or aromatic group having extended pi -conjugation (preferably phenyl or napthyl);R2=H or alkyl group (preferably H);R3, R4, R6 and R7=alkyl, alkoxy, or alkylsulfane groups (all optionally substituted with heteroatoms) or H (preferably hexyl, heptyl, 2-ethylhexyl, methoxy, butyloxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, or hexylsulfane);X=halogen (preferably bromine, chlorine, or iodine);R8=aromatic group or aromatic group having extended pi -conjugation (preferably biphenylene, fluorene, 1,2-diphenylethene, or 1,2-distyrylben);andR9 and R10=alkyl, alkoxy, or alkylsulfane group (all optionally substituted with heteroatom) or H (preferably ethyloxy group).    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer comprises poly(methylacrylate), poly(methylmethacrylate), poly(styrene), poly(a-methyl styrene), or other glassy polymers. SPECIFIC COMPOUNDS - 11 Compounds are specified as compound (I) e.g. 4-bromo-2,5-diheptylbenzaldehyde (Ia); 2,5-dihexyloxy-4-bromobenzaldehyde; 4-bromo-2,5-bis(hexylthio)benzaldehyde; 5-bromo-2,6-bis(hexyloxy)-1-naphthaldehyde, 2,5-dimethoxy-4-bromobenzaldehyde. 10 Compounds are specified as compound (II) e.g. 1,4-dibromo-2,5-diheptylbenzene; 2,5-dihexyloxy-1,4-dibromobenzene; (2,5-dibromo-1,4-phenylene)bis (hexylsulfane); 1,5-dibromo-2,6-bis(hexyloxy)naphthalene; 1,4-dibromo-2,5-dimethoxybenzene. 6 Compounds are specified as compound (III) e.g. 8-bromo-3,6-diethoxybiphenylene-1-carbaldehyde; 4,5,8-tribromo-3,6-diethoxybiphenylene-1-carbaldehyde; 5-bromo-2,7-diethoxy-9H-fluorene-4-carbaldehyde; 2-(2-bromo-5-ethoxystyryl)-4-ethoxybenzaldehyde; 2-(2-bromo-4-ethoxystyryl)-5-ethoxybenzaldehyde.    EXAMPLE - No suitable example given.