Synthesis, Structures, and Photoluminescent Properties of Cyclometalated Platinum(II) Complexes bearing Upper-Rim Phosphinated Calix[4]arenes

Abstract

Experimental details and spectroscopic data of [(PtThpyCl) 2 L n ], [Pt(Thpy)PPh 3 Cl], and [Pt(Thpy)PPh 3 (CH 3 CN)]ClO 4 , crystallographic data and photophysical spectra. S 2 Experimental Section Materials and General Procedures. [Pt(Thpy)(HThpy)Cl] was prepared by literature method. 1 Acetonitrile for photophysical measurements was distilled over potassium permanganate and calcium hydride. Dichloromethane for photophysical studies was washed with concentrated sulfuric acid, 10 % sodium hydrogen carbonate, and water, dried by calcium chloride, and distilled over calcium hydride. All other solvents were of analytical grade and purified according to conventional methods. 2 p-tert-Butylcalix[4]arene was purchased from Alfa Aesar. Instrumentation and Physical Measurements. Fast atom bombardment (FAB) mass spectra were obtained on a Finnigan Mat 95 mass spectrometer with a 3-nitrobenzyl alcohol matrix, whereas electrospray mass spectra were obtained on a LCQ quadrupole ion trap mass spectrometer. High-resolution ESI mass spectra were obtained from a Waters Micromass Q-Tof Premier quadrupole time-of-flight tandem mass spectrometer. 1 H (500 MHz), 13 C (126 MHz) and 31 P (202 MHz) NMR spectra were performed on DPX 500 Bruker FT-NMR spectrometer with chemical shifts (in ppm) relative to tetramethylsilane ( 1 H and 13 C) and H 3 PO 4 ( 31 P) as references. Elemental analyses were performed by the Institute of Chemistry at the Chinese Academy of Sciences, Beijing. UV-vis spectra were recorded on a Perkin Elmer Lambda 19 UV/vis spectrophotometer. Emission and Lifetime Measurements. Steady-state emission spectra were recorded on a Fluorolog-3 Model FL3-21 spectrophotometer. Solution samples for measurements were S 3degassed with at least four freeze-pump-thaw cycles. Low-temperature (77 K) emission spectra for glassy solutions and solid-state samples were recorded in 5 mm diameter quartz tubes, which were placed in a liquid nitrogen Dewar equipped with quartz windows. The emission spectra were corrected for monochromator and photomultiplier efficiency and for xenon lamp stability. Emission lifetime measurements were performed with a Quanta Ray DCR-3 pulsed Nd:YAG laser system (pulse output 355 nm, 8 ns). The emission signals were detected by a Hamamatsu R928 photomultiplier tube and recorded on a Tektronix TDS 350 oscilloscope. Errors for λ values (± 1 nm), τ (± 10 %), Φ (± 10 %) were estimated.Luminescence quantum yields were determined using the method of Demas and Crosby 3 with [Ru(bpy) 3 ]Cl 2 in degassed acetonitrile as a standard reference solution (Φ r = 0.062) and calculated according to the following equation: Φ s = Φ r (B r /B s )(n s /n r ) 2 (D s /D r ), where the subscripts s and r refer to sample and reference standard solution respectively, n is the refractive index of the solvents, D is the integrated intensity, and Φ is the luminescence quantum yield. The quantity B was calculated by B = 1 − 10 −AL , where A is the absorbance at the excitation wavelength and L is the optical path length. . 5,26,27,arene ...

Conversion of imine ligands in allyl–nickel(II) complexes

“…This gave a great impetus to syntheses of a wealth of new diimine ligands and their metallo-complexes with different transition metals [19][20][21][22][23][24][25][26][27][28][29][30][31][32].…”

Efficient Singlet Oxygen Generation by Luminescent 2‐(2′‐Thienyl)Pyridyl Cyclometalated Platinum(II) Complexes and Their Calixarene Derivatives

“…We also envision that 2‐(2′‐thienyl)pyridyl platinum(II) complexes incorporated into upper‐rim phosphinated calix[4]arenes, as reported previously by us (30), could be developed as photosensitizing hosts towards target guests. Therefore, we describe the production of singlet oxygen by complexes [(PtThpyCl) 2 L] ( 6 ) and [{PtThpy(CH 3 CN)} 2 L](ClO 4 ) 2 ( 7 ), where L is 5,17‐bis(diphenylphosphino)‐25,26,27,28‐tetra‐ n ‐butoxycalix[4]arene.…”

“…Synthesis and characterization of 1 , 2 and 4 have been reported previously (28–30), whereas complexes 3 and 5 were prepared by similar synthetic procedures as developed for 2 , except pyridine was used as solvent in the reactions using precursors 1 and 4, respectively. Complexes 3 and 5 were characterized by 1 H and 13 C{ 1 H} spectroscopy, ESI mass spectrometry and X‐ray crystallography (see Supporting Information).…”

“…Apart from organic photosensitizers commonly used for the generation of singlet oxygen, transition metal complexes have recently been shown to be attractive alternatives due to their strong absorptions in the UV‐visible region, long‐lived triplet metal‐to‐ligand charge transfer (MLCT) states, high emission quantum efficiencies of the triplet‐state, and high photostability (17–23). In the past decades, Che and coworkers investigated the photoluminescent properties of cyclometalated platinum(II) complexes, namely [Pt(C^N^N)R 1 ] n+ bearing tridentate C‐deprotonated 6‐phenyl‐2,2′‐bipyridine [C^N^N] − and related ligands (24–27), and [Pt(Thpy)R 2 R 3 ] n+ with bidentate Thpy ligand (HThpy = 2‐(2′‐thienyl)pyridine) (28–30). Their spectroscopic characteristics were reported to vary significantly with the electronic properties and structure of the ancillary ligands (R 1−3 ).…”

“…Synthesis. Preparation and characterization of [Pt(Thpy)PPh 3 Cl] ( 1 ) and [Pt(Thpy)PPh 3 (CH 3 CN)]ClO 4 ( 2 ) were documented by us previously (30). Using similar synthetic procedures adapted for 2 except pyridine was used as solvent, [Pt(Thpy)PPh 3 (py)]ClO 4 ( 3 ) and [Pt(Thpy)(HThpy)py]ClO 4 ( 5 ) were obtained by using [Pt(Thpy)PPh 3 Cl] ( 1 ) and [Pt(Thpy)(HThpy)Cl] ( 4 ) as precursors, respectively.…”