Synthesis and ion-binding studies of platinum(II) phenanthroline complexes containing crown ether moiety

Abstract

Two new benzo-[15]-crown-5 attached phenanthroline platinum(II) complexes with the general formula Pt(phen)X 2 , where X = Cl (1), C≡CC 6 H 5 (2) have been synthesized, and their absorption and luminescence response towards metal ions have been studied. Keywords: phenanthroline platinum(II) complex, MLCT excited state, benzo-[15]-crown-5 phenanthroline.www.scichina.com www.springerlink.com 1005 ) Square-planar platinum(II) polypyridyl complexes represent an important class of compounds that possess a rich range of spectroscopic and photophysical properties [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . Some of them have demonstrated promise in wide-ranging applications including optical power limiting [4] , electroluminescence [5,6] , photocatalysts [7][8][9] and multi-electron-transfer processes [10,11] . Recently, the design of luminescent sensors for metal ions has been extended to the utilization of platinum(II) polypyridyl complexes, and ion-binding studies of platinum(II) terpyridyl or cyclometalated complex by us [12][13][14] and others [15][16][17] have been reported. In this communication, we wish to describe the synthesis of two new benzo-[15]-crown-5 attached phenanthroline platinum(II) complexes with the general formula Pt(phen)X 2 , where X = Cl (1), C≡CC 6 H 5 (2), and their absorption and luminescence response towards metal ions.The synthetic strategies for making the complexes 1 and 2 are summarized in Scheme 1. Pt(phen)Cl 2 (1) was prepared by the reaction of benzo-[15]-crown-5 phenanthroline with Pt(DMSO) 2 Cl 2 in acetone solution at 20 ℃ . Benzo-[15]-crown-5 phenanthroline and Pt(DMSO) 2 Cl 2 were made according to refs. [18-21].Complex 2 [Pt(phen)(C≡CC 6 H 5 ) 2 ] was prepared by reaction of complex 1 with excess amount of phenylacetylene in DMF in the presence of CuI and triethylamine at room temperature. 1 and 2 were obtained as yellow crystal in 72% and 81% chemical yield, respectively. The identity of complexes 1 and 2 was confirmed by 1 H NMR spectroscopy, mass spectrometry and satisfactory elemental analysis.UV/vis spectra were measured on a Shimadzu UV-1601 PC spectrophotometer. As shown in Fig. 1, complexes 1 and 2 in acetonitrile solution exhibit intense vibronic-structured absorption bands at λ < 350 nm with extinction coefficients (ε) on the order of 10 4 dm 3 mol −1 cm −1 , and less intense band at 400-500 nm with ε on the order of 10 3 dm 3 mol -1 cm -1 . The absorption spectral properties were found to follow Beer's Law below saturated concentration (ca. 5 × 10 −5 mol dm −3 ) in this solvent, suggesting no any significant complex aggregation occurred. Table 1 summarizes the band maxima and the extinction coefficients for the transitions. The absorption bands at λ < 350 nm are assigned to the intraligand (IL) transition of phenanthroline or/and acetylide ligands as well as the charge transfer transition involved in the Pt-C≡CR moieties of complex 2 [22][23][24] . The low energy absorption bands at 400-500 nm are assignable to the charge transfer transition from a f...

Novel N^C^N-cyclometallated platinum complexes with acetylide co-ligands as efficient phosphors for OLEDs

“…The cyclometallated N^C^N Pt(II) chloride precursors [PtL 3 Cl] and [PtL 6 Cl] were synthesized as previously reported {HL 3 ¼ 5-methyl-1,3-di(2-pyridyl)benzene and HL 6 ¼ 5-mesityl-1,3-di(2pyridyl)benzene}. 17,21 Various attempts to substitute the chloride in these complexes by the ethynyl-3,5-difluorobenzene anion following Sonogashira's synthetic route, which has been shown to be suitable for preparing acetylide derivatives of cyclometallated N^N^C and O^N^N Pt(II) complexes, 14,26,27 were unsuccessful, despite the screening of different catalytic systems (for example, CuI-iPr 2 NH, CuI-Et 3 N, CuOAc-iPr 2 NH, and CuOAc-Et 3 N). However, [PtL 3 -C^C-C 6 H 3 F 2 ] and [PtL 6 -C^C-C 6 H 3 F 2 ] were readily obtained in quantitative yield by reaction of PtL n Cl with the acetylide anion prepared by deprotonation of 3,5-difluorophenylacetylene with sodium methoxide, as shown in Scheme 1.…”

“…17,21 Various attempts to substitute the chloride in these complexes by the ethynyl-3,5-difluorobenzene anion following Sonogashira's synthetic route, which has been shown to be suitable for preparing acetylide derivatives of cyclometallated N^N^C and O^N^N Pt(II) complexes, 14,26,27 were unsuccessful, despite the screening of different catalytic systems (for example, CuI-iPr 2 The new Pt(II) acetylide complexes were fully characterized by elemental analyses and by IR and NMR spectroscopies.…”

Optical properties of highly planar diketopyrrolopyrrole derivatives fixed by coordinate bonds

“…cis-Dichlorobis(dimethylsulfoxide)platinum (II) [cis-PtCl 2 (dmso) 2 ] was prepared according to the literature method. 18 Other chemicals were purchased and used without further purification.…”

Oxidation of 2,9‐Diphenyl‐1,10‐phenanthroline to Generate the 5,6‐Dione and Its Subsequent Alkylation Product

“…In reaction with o‐phenylenediamines, phenazine rings can be formed . Moreover, some 1,10‐phenanthroline‐5,6‐diones can be easily reduced with hydrazine in aqueous acid to form the corresponding catechol . The catechol can then also be derivatized in a variety of ways; for example, by alkylation of the oxygens via a Williamson reaction .…”