Substituted R2 groups are exemplified by, but not limited to, halogen such as chlorine and fluorine, alkoxycarbonyl such as described by formula ???(CH2)aC(O)O(CH2)bCH3, alkoxy substitution such as described by formula ???(CH2)aO(CH2)bCH3, and carbonyl substitution such as described by formula ???(CH2)aC(O)(CH2)bCH3, where a???0 and b???0.