TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The photochromic metal oxide entity is formed in the matrix by exposing a monometallic carbonyl precursor of the photochromic metal oxide entity to ultraviolet light. Preferred Components: The photochromic metal oxide entity is a photochromic transition metal oxide, and/or photochromic bronze. The photochromic transition metal oxide is compound of formula MxOy. The photochromic bronze is compound of formula MxOy+1A2. The photochromic transition metal oxide is W3O8, ranging in various stoichiometric forms of up to W75O200; Mo3O8, ranging in various stoichiometric forms of up to Mo75O200; Fe3O4, ranging in various stoichiometric forms of up to Fe75O100; Ti3O2, ranging in various stoichiometric forms of up to Ti75O50; V3O7, ranging in various stoichiometric forms of up to V75O175; and/or Nb3O3, ranging in various stoichiometric forms of up to Nb75O75, (preferably W3O8, ranging in various stoichiometric forms of up to W75O200; or Mo3O8, ranging in various stoichiometric forms of up to Mo75O200). The photochromic bronze is W3O9H2, ranging in various stoichiometric forms of up to W75I201H2; Mo3O9H2, ranging in various stoichiometric forms of up to Mo75O201H2; Fe3O5H2, ranging in various stoichiometric forms of up to Fe75O101H2; Ti3O3H2, ranging in various stoichiometric forms of up to Ti75O51H2; V3O8H2, ranging in various stoichiometric forms of up to V75O176H2; and/or Nb3O4H2, ranging in various stoichiometric forms of up to Nb75O76H2 (preferably W3O9H2, ranging in various stoichiometric forms of up to W75I201H2; or Mo3O9H2, ranging in various stoichiometric forms of up to Mo75O201H2). The monometallic carbonyl precursor is W(CO)6, Mo(CO)6, and/or Fe3(CO)12. The bimetallic coordination complex is a Ru(II) diimine-metal oxide polymetallic, and/or Os(II) diimine-metal oxide polymetallic.M=transition metal present as a mixture of different oxidation states (preferably titanium, tungsten, molybdenum, iron, vanadium, niobium and/or zinc);x= less than or equal to 100;y= less than or equal to 300;A=H, Li, Na, K, Rb, Cs or Fr.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The matrix comprises unpolished Coming code 7930 porous Vycor glass or tetramethoxysilane/methanol/water xerogel. The tetramethoxysilane/methanol/water xerogel has been dried at 180-200 degrees C. The bimetallic coordination complex is ((bis-2,2'-bipyridiyl)M'(2,3 dipyridylpyrazine)X'O3)2+.M'=Ru or OS;X'=W or M. EXAMPLE - No suitable example given.