6 carbon atoms the term u201c cycloalkyl u201d is used herein to refer to an alkyl group as previously described that is cyclic in structure and has about 3 to about 10 carbon atoms e g 3 8 carbon atoms desirably about 5 to about 3 carbon atoms the terms u201c substituted alkyl u201d u201c substituted alkenyl u201d u201c substituted alkynyl u201d and u201c substituted cycloalkyl u201d refer to alkyl alkenyl and alkynyl groups respectively having one or more e g 2 or 3 substituents including without limitation halogen cn oh no 2 amino aryl heteroaryl alkoxy aryloxy alkylcarbonyl alkylcarboxy and arylthio which groups can be optionally substituted these substituents can be attached to any carbon of an alkyl alkenyl alkynyl or cycloalkyl group provided that the attachment constitutes a stable chemical moiety the term u201c heteroalkyl u201d is used herein to refer to an alkyl or substituted alkyl group as previously described that contains heteroatoms in the backbone of the alkyl moiety the heteroalkyl has carbon atoms and one or more heteroatoms including nitrogen oxygen and sulfur atoms desirably the heteroalkyl has 1 to about 4 heteroatoms in the backbone of the ring the heteroalkyl group typically has 1 to about 10 carbon atoms and desirably 1 to about 8 e g 6 carbon atoms the term u201c aryl u201d as used herein refers to an aromatic system e g of about.