Benzophenone/thioxanthone derivatives and their use in photopolymerizable compositions

A photoinitiator having the Formula (I):

• having the Formula (II):
• combinations thereof,
• wherein at least one R is —S—X1—Y1 attached to an aromatic ring in an ortho, meta, or para position, wherein S is a sulfur atom, X1 is a linear, branched or cyclic alkyl or aliphatic group or an aromatic ring having 1 to 10 carbon atoms and accompanying heteroatoms, and Y1 is —OH, —SH, or —NR*2, wherein each R* is independently selected from hydrogen or a linear, branched or cyclic alkyl group or an aromatic ring having 1 to 10 carbon atoms, and a remaining R is a linear, branched or cyclic alkyl or aliphatic group having 1 to 16 carbon atoms, hydrogen, —S—X1—Y1, wherein S, X1, and Y1 are defined as above, or -Z-X2—Y2, wherein Z is S, O or NR*, wherein R* is selected from hydrogen or a linear, branched or cyclic alkyl group or an aromatic ring having 1 to 10 carbon atoms, X2 is a linear, branched or cyclic alkyl group or an aromatic ring having 1 to 10 carbon atoms, and Y2 is —OH, —SH, or —NR*2, wherein each R* is independently selected from hydrogen or a linear, branched or cyclic alkyl group or an aromatic ring having 1 to 10 carbon atom;
• or
• wherein at least one R is
• attached to an aromatic ring in an ortho, meta, or para position and wherein R1, R2 and R3 are independently selected from a linear, branched, or cyclic alkyl or aliphatic group having 1 to 16 carbon atoms and accompanying heteroatoms or —CH2COOR4 wherein R4 is a linear alkyl having 1 to 16 carbon atoms and is attached to the sulfur atom, and the remaining R is a linear, branched, or cyclic alkyl or aliphatic group having 1 to 16 carbon atoms or hydrogen.