TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The oxidation of chlorin is performed by exposing the chlorin to alumina. It may be conducted in toluene and in the presence of an oxidizing agent. The hydroxychlorin is oxidized at 0-100degreesC in an aromatic organic solvent (preferably toluene).Preferred Compound: The chlorin is preferably of formula (I) and especially a C-methylated chlorin or metalated.M = metal of Zn, Mg, Pt, Pd, Sn or Al or absent;K1-K4 = hetero atoms of N, O, S, Se, Te or CH;A = H, aryl, phenyl, cycloalkyl, alkyl, alkenyl, alkynyl, halogen, alkoxy, alkylthio, perfluoroalkyl, perfluoroaryl, pyridyl, cyano, thiocyanato, nitro, amino, alkylamino, acyl, sulfoxyl, sulfonyl, imido, amido or carbamoyl;S1-S14 = A or spiroalkyl or where S1 and S2, or S6 are trans-substituted linking groups of Q1 and Q2 or S10 and S12 or S9 and S11 are trans-substituted linking groups of Q1 and Q2 or S7 and S13 together can be =O;Q1, Q2 = linking groups of formula -(R1-R2)n-R3-Y;n = 0-10;R1-R3 = ethene, ethyne, or optionally substituted aryl or heteroaryl with A; andY = (un)protected reactive substituent of hydroxy, thio, seleno, telluro, ester, carboxylic acid, phosphonic acid, alkylthiol, formyl, halo, alkenyl, alkynyl, haloalkyl, dialkyl phosphonate, alkyl sulfonate, alkyl carboxylate, acetylacetone or dialkyl boronate.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Agent: The oxidizing agent is oxygen or air. Preferred Definitions:    S4, S7-S14 = alkyl;    M = Zn or Mg;    K1-K4 = O, S, CH or preferably N    S8 or S14 is H. S9 and S11 are trans-substituted linking groups of Q1 and Q2.    EXAMPLE - A mixture of zinc-1a (Zn-1a) and basic alumina in toluene at room temperature was stirred in reaction vessel exposed to air for 36 hours. Elution of chlorin species and analysis determined three components which were separated as Zn-1a, Oxo-Zn-1a and hydroxychlorin (Ho-Zn-1a) on silica. Oxidation of Zn-1a with alumina was attempted at 50 degreesC for 15 hours. The starting material was completely consumed yielding a mixture of HO-Zn-1a and Oxo-Zn-1a. Oxidation of the mixture with DDQ afforded Oxo-Zn-1a in 54% yield.