A new series of luminescent phosphine stabilised platinum ethynyl complexes

Abstract

A series of cis-platinum ethynyl complexes with the general formula cis-[Pt(dppe)(C[triple bond]CR)2](dppe = 1,2-bis(diphenylphosphino)ethane; R = C6H4-p-NO2 1, C6H4-p-CH3 2, C6H4-p-C[triple bond]CH 3 and C6H4-p-C6H4-p-C[triple bond]CH 4) have been prepared by the coupling reaction of cis-[Pt(dppe)Cl2] with two equivalents of the appropriate alkyne. The new complexes have been fully characterized by spectroscopic techniques, and the cis square planar arrangement at the platinum centre has been confirmed by single-crystal X-ray diffraction studies of complexes 1, 2 and 4. The absorption spectra of the complexes 1-4 are dominated by a pi-->pi* band that contains some platinum (n + 1) p orbital character. The position of the band is dependent on the electron donating or withdrawing properties of the ethynyl substituents, R. Complex 1 displays a triplet emission in the green, at room temperature, while complexes 2-4, display singlet emissions in the blue. Again, the difference can be attributed to the nature of the R substituents.

Synthesis and Antibacterial Activities of Sugar-containing Platinum Ethynyl Complexes

“…These bands have been assigned to the π-π * transition of the acetylenic fragment with LMCT character due to the mixing between π * (C≡C-R) and platinum (n + 1)p orbital. Similar spectroscopic features are reported in the related metal acetylide systems (Wong et al 2004, Saha et al 2005, Sina et al 2015. Antibacterial activity: The antibacterial activities of sugar-containing iodo compound 1, ethynyl compounds 2 and 3, and platinum complexes 4 and 5 were tested against bacteria Escherichia coli, Proteus penneri, Klebsiella oxytoca and Pseudomonas aeruginosa.…”

“…UV-Vis spectroscopy is used to understand the π-interaction between the metal and ethynyl group in the metal ethynyl complexes (Saha et al 2005, Younus et al 1998, Fujikura et al 1975. A broad band at 250-360 nm was observed in the spectrum of mono-and bis-ethynyl complex 4 and 5.…”

“…Though the bis-complex 5 was also formed, its isolated yield is only 20 %. Dehydrogenation reaction always gives platinum bis-acetylide when ethynyl ligand is used in excess (Saha et al 2005). Mono-acetylides of platinum is only obtained when platinum chloride precursor is used in excess under mild reaction condition (Zhou et al 2009), sometimes even without catalyst (Amato et al 2001).…”

“…The stretching frequency of (C≡C) is shifted from 2117 to 2081 cm -1 when the remaining chloride was replaced by the second acetylide group. The M-C and C≡C stretching frequencies are used to determine the geometry of the square planar metal ethynyl complexes (Sonogashira et al 1978, Long et al 2002, Saha et al 2005. For example, cis-[(PBu 3 ) 2 Pt(C≡C-C≡CH) 2 ] has a C 2v symmetry and showed two absorption bands for each v(C≡C) and v(M-C) (Sonogashira et al 1978).…”

Conjugated Platinum-Poly-Ynes with extended Arylene Ethynylenes

“…In recent works, the authors reported the synthesis of platinum-poly-ynes with phosphines other than tri-n-butylphosphine. These include platinum ethynyl conplexes with 1,2-bis(diphenylphosphinoethane), dppe, - (Saha et al 2005) and tri-tolylphosphines containing platinum poly-yne polymers i.e.…”