Syntheses, Electrochemical, Linear Optical, and Cubic Nonlinear Optical Properties of Ruthenium-Alkynyl-Functionalized Oligo(phenylenevinylene) Stars

摘要

The syntheses of trans-[Ru(CCC6H4-4-CHO)(CCC6H4-4-R)(dppe)(2)] (R=H (9a), NO2 (9b), CHO (9c), CCC6H3-3,5-Et-2 (9d), (E)-CHCHC6H4-4-tBu (9e); dppe=1,2-bis(diphenylphosphino)ethane), trans-[Ru(CCC6H4-4-R)Cl(dppe)(2)] (R=CCC6H3-3,5-Et-2 (11a), (E)-CHCHC6H4-4-tBu (11b), (E)-CHCHC6H4-4-NO2 (11c)), 1,2,4,5-{trans-[(dppe)(2)(RC6H4CC)Ru{CCC6H4-4-(E)-CHCH}]}(4)C6H2 (R=H (14a), CCC6H3-3,5-Et-2 (14b), (E)-CHCHC6H4-4-tBu (14c)), 1-I-3,5-{trans-[(L-2)(2)(R)Ru{CCC6H4-4-(E)-CHCH}]}(2)C6H3 (L-2=1,1-bis(diphenylphosphino)methane (dppm)), R=Cl (15a); L-2=dppe, R=CCPh (15b), R=CCC6H4-4-NO2 (15c)), 1-Me3SiCC-3,5-{trans-[(L-2)(2)(R)Ru{CCC6H4-4-(E)-CHCH}]}(2)C6H3 (L-2=dppm, R=Cl (16a); L-2=dppe, R=CCPh (16b)), 1-HCC-3,5-{trans-[(dppe)(2)(R)Ru{CCC6H4-4-(E)-CHCH}]}(2)C6H3 (R=Cl (17a), R=CCPh (17b)), and 1,3,5-{trans-[(dppe)(2)(3,5-R-2-C6H3CC)Ru{CCC6H4-4-(E)-CHCH}]}(3)C6H3 (R=(E)-CHCHC6H4-4-CC-trans-[Ru(CCPh)(dppe)(2)] (18)) are reported together with those of the precursor alkynes 1-RCC-3,5-Et2C6H3 (R=SiMe3 (2), H (3), C6H4-4-CCSiMe3 (5), C6H4-4-CCH (6)). The identities of 9c, 9d, 9e, 11a, and trans-[Ru{CCC6H4-4-(E)-CHCHC6H4-4-tBu}(2)(dppe)(2)] (12 and 12) were confirmed by single-crystal X-ray diffraction studies. The electrochemical properties of 9a-e, 11a-b, 14a-c, 15a-c, 16b, 17a, 17b, and 18 were assessed by cyclic voltammetry; the studies reveal that potentials for the fully/quasi-reversible metal-centered oxidation processes decrease upon introduction of solubilizing alkyl substituents and increase upon increasing acceptor substituent strength; other structural variations have little impact. UV/Vis-NIR spectroscopic studies on these complexes reveal lowest-energy metal-ligand charge transfer (MLCT) bands that redshift upon increasing the acceptor substituent strength, blueshift on alkyl incorporation, and gain in intensity on progression from linear to star complexes. Low-temperature UV/Vis-NIR spectroelectrochemical studies of 14a-c show the appearance of an intense low-energy band at 7400-7900cm(-1) that is redshifted upon -system lengthening and alkyl substituent incorporation. The cubic nonlinear optical properties of 9d, 9e, 14a-c, 15a-c, 16b, 17a,b, and 18 were assayed by femtosecond Z-scan studies at benchmark wavelengths (750 and 800nm) in the near-IR region, with nonlinearity increasing upon nitro incorporation; the values for the E-ene-linked dendrimers in these studies are much larger than yne-linked analogues.