prov:value
| - ???C(O)-A, ???SO2-A, ???PO(OR)-A, where A is hydroxy, alkoxy, aryloxy, amino, alkylamino, dialkylamino, or ???OM, where M is a cation selected from the group consisting of ammonium, tetra-alkyl ammonium, Na, K, Mg, and Zn, and R is hydroxyl or alkoxy; Y, Z and W are linkers independently selected from the group consisting of a ring containing up to 20 atoms and a chain of up to 20 atoms, provided
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