||Three series of organic octupolar molecules, derived respectively from 2,4,6-tris(styry1)-1,3,5-triazine, 2,4,6-triphenyl-1,3,5-tiazine and 1,3,5-tris(styryl)benzene, were synthesized and are reported in Chapters 3, 4, and 7. Treatment of 2,4,6-trimethyl-1,3,5-triazine with different aromatic aldehydes in the presence of KOH afforded octupolar molecules with a 1,3,5-triazine core. Treatment of 2,4,6-tris(4-bromophenyl)-1,3,5-triazine with terminal acetylenes in the presence of Pd(PPh3)4/CuI and NEt3 also produced octupolar derivatives of 1,3,5-triazine. Reaction of 1,3,5-tris(diethoxyphosphorylmethyl)benzene with benzaldehydes in the presence of KOBut and 18-crown-6 gave corresponding octupoalr molecules with a benzene core. The photophysical properties of these compounds were investigated. The first hyperpolarizabilities, β, of the new octupolar molecules were measured by 1500, 1600 or 1700 nm HRS techniques. The relationship of second-order NLO property/chemical structure for these compounds has been discussed. Chapter 5 reports the synthesis and characterization of three dendrimers with one or three 1,3,5-triazine cores. The second-order NLO properties of these dendrimers have been studied. The synthesis and NLO properties of trimetallic complexes derived respectively from 2,4,6-tris(styryl)-1,3,5-trazine and 2,4,6-triphenyl-1,3,5-triazine are described in Chapters 6 and 7. From reactions of 2,4,6-(E)-[4-(HC≡C)-C6H4CH=CH]3-1, 3,5-(CN)3, or 2,4,6-[4-(HC≡C)-C6H4]3-1,3,5-(CN)3, with complexes such as RuClCp*(dppe), cis-RuCl2(dppe)2, RuHCl(CO)(PPh3)3 and AuCl(PPh3), many trimetallic complexes with metal-acetylide or metal-vinyl linkage were prepared. The electrochemistry of the ruthenium acetylide complexes has been investigated. The β values of these complexes were measured by 1064 nm HRS techniques. Chapter 8 presents the synthesis of borazine derivatives. Treatment of [Cp*Ru(dppe)]+ with B-triethynyl-N-trimethylborazine and piperidine produces the trimetallic complex [Cp*Ru(dppe)(C≡C)]3B3N3Me3. Reaction of RuHCI(CO)(PPh3)3 with B-triethynyl-N-trimethylborazine produces the trimetallic complex [RuCl(CO)(PPh3)2(CH=CH)]3B3N3Me3. Chapter 9 presents the synthesis and electrochemical properties of bimetallic ruthenium complexes. Reactions of RuCl(dppm) (η5-C9H7) with terminal alkynes HC≡C(C6H4)nC≡CH (n = 1, 2) in the presence of TlPF6 and NaOBut afford ruthenium complexes [(η5-C9H7)(dppmn)Ru]2 [μ-C≡C(C6H4)nC≡C]. Treatment of RuH(dppm)(η5-C9H7) with HC≡C(C6H4)nC≡CH (n = 1, 2) in refluxing toluene gives ruthenium complexes [(η5-C9H7)(dppm)Ru]2[μ-CH=CH(C6H4)nCH=CH]. The electrochemical properties of the biruthenium complexes are investigated.