Louise Male

Synthesis, characterisation and optical spectroscopy of diynes and poly-ynes containing derivatised fluorenes in the backbone

A series of trimethylsilyl-protected and terminal mono- and bis-alkynes based on 9,9-dioctylfluorene, 2-(trimethylsilylethynyl)-9,9-dioctylfluorene 1a, 2-ethynyl-9,9-dioctylfluorene 1b, 2,7-bis(trimethylsilylethynyl)-9,9-dioctylfluorene 2a, 2,7-bis(ethynyl)-9,9-dioctylfluorene 2b, have been synthesised. Reaction of trans-[(PnBu3)2PtCl2] with 2 equivalents of the terminal ethyne 1b yields the mononuclear platinum(II) diyne 3, reaction of trans-[(Ph)(Et3P)2PtCl] with 0.5 equivalents of the diterminal ethyne 2b gives the dinuclear platinum(II) diyne 4 while 1 ∶ 1 reaction between trans-[(PnBu3)2PtCl2] and 2b gives the platinum(II) poly-yne 5. Treatment of 2,5-dioctyloxy-1,4-diiodobenzene with 1b in 1 ∶ 2 stoichiometry produces the organic di-yne 6 while 1 ∶ 1 reaction between 2,5-dioctyloxy-1,4-diiodobenzene and 2b, 2,7-bis(ethynyl)fluorene or 2,7-bis(ethynyl)fluoren-9-one produces the organic co-poly-ynes 7–9. All the new materials have been characterised by analytical and spectroscopic methods and the single crystal X-ray structures of 2a and 3 have been determined. The diynes and poly-ynes are soluble in organic solvents and are readily cast into thin films. Optical spectroscopic measurements reveal that the attachment of octyl side-chains on the fluorenyl spacer reduces inter-chain interaction in the poly-ynes while a fluorenonyl spacer creates a donor–acceptor interaction along the rigid backbone of the organometallic poly-ynes and organic co-poly-ynes.

Synthesis and characterisation of new acetylide-functionalised aromatic and hetero-aromatic ligands and their dinuclear platinum complexes

A new series of rigid rod protected and terminal dialkynes with extended π-conjugation through aromatic and hetero-aromatic linker units in the backbone, 2,5-bis(trimethylsilylethynyl)-1-(2-ethylhexyloxy)-4-methoxybenzene 1a, 2,5-bis(ethynyl)-1-(2-ethylhexyloxy)-4-methoxybenzene 1b, 5,8-bis(trimethylsilylethynyl)quinoline 2a, 5,8-bis(ethynyl)quinoline 2b, 2,3-diphenyl-5,8-bis(trimethylsilylethynyl)quinoxaline 3a, 2,3-diphenyl-5,8-bis(ethynyl)quinoxaline 3b, 4,7-bis(trimethysilylethynyl)-2,1,3-benzothiadiazole 4a and 4,7-bis(ethynyl)-2,1,3-benzothiadiazole 4b, has been synthesised. Treatment of the complex trans-[Pt(Ph)(Cl)(Et3P)2] with half an equivalent of the diterminal alkynes 1b–4b in iPr2NH–CH2Cl2, in the presence of CuI, at room temperature, afforded the platinum(II) di-yne complexes trans-[(Et3P)2(Ph)Pt–CC–R–CC–Pt(Ph)(Et3P)2] [R = 1-(2-ethylhexyloxy)-4-methoxybenzene-2,5-diyl 1c, quninoline-5,8-diyl 2c, 2,3-diphenylquinoxaline-5,8-diyl 3c, 2,1,3-benzothiadiazole-4,7-diyl 4c] in good yields. The new acetylide-functionalised ligands and the platinum(II) σ-acetylide complexes have been characterised by analytical and spectroscopic methods and X-ray single crystal structure determinations for 2c–4c. The absorption spectra of the complexes 2c–4c show substantial donor–acceptor interaction between the platinum(II) centres and the conjugated ligands. The photoluminescence spectra of 1c–3c show characteristic singlet (S1) and triplet (T1) emissions. Both the singlet and triplet emissions as well as the absorption decrease in energy with increasing electronegativity of the spacer groups along the series 1c–4c.

Structural characterisation of a series of acetylide-functionalised oligopyridines and the synthesis, characterisation and optical spectroscopy of platinum di-ynes and poly-ynes containing oligopyridyl linker groups in the backbone

A series of trimethylsilyl-protected bis(ethynyl)oligopyridine derivatives Me3SiCC–R–CC–SiMe3 (R = 2,2′-bipyridine-5,5′-diyl (1a), 2,2′-bipyridine-6,6′-diyl (2a), 2,2′:6′,2″-terpyridine-6,6″-diyl (3a), 4′-phenyl-2,2′:6′,2″-terpyridine-6,6″-diyl (4a)) has been synthesised and 2a–4a have been characterised by single crystal X-ray crystallography. The corresponding terminal di-ynes H–CC–R–CCH (1b–4b) and their dinuclear platinum(II) complexes trans-[(Et3P)2(Ph)Pt–CC–R–CC–Pt(Ph)(Et3P)2] (1M–4M) have been characterised spectroscopically and by single-crystal X-ray crystallography for 2M. Novel platinum(II) poly-yne polymers trans-[Pt(PBun3)2–CC–R–CC–]n (1P–4P) containing the oligopyridyl linker groups in the backbone have been synthesised by the CuI-catalysed dehydrohalogenation polycondensation reaction of 1b–4b and trans-[(Bu3P)2PtCl2] in Pri2NH–CH2Cl2. The polymeric materials exhibit decreasing thermal stability with increasing number of pyridine units in the linker group. In the absorption and phosphorescence spectra, the platinum(II) poly-yne and di-yne complexes 1P, 1M show red shifts whereas the complexes 2P–3P, 2M–3M show blue shifts of the S1 and T1 states. At room temperature, the phosphoresence spectra indicate some excimer formation whereas at 10 K, only intra-chain emission occurs. The results of the photophysical studies are compared with those obtained for other platinum(II)-containing poly-ynes and related organometallic polymers.

Trans-Bis(carbazol-3-ylethynyl)bis(tri-n-butylphosphine)platinum(II)

The title compound, [Pt(C12H27P)(2)(C14H8N)(2)], is a mononuclear Pt-II di-yne exhibiting pi-conjugation along the molecular backbone. It is used as a model species for rigid-rod platinum poly yne compounds of which it is a precursor. Such compounds are of interest due to the extended pi-conjugation through the hetero-aromatic linker unit in the backbone.

5,8-Diethynyl-2,3-di­phenyl­quinoxaline

The title compound, C24H14N2, is a rigid-rod terminal dialkyne exhibiting extended π-conjugation through the heteroaromatic linker unit in the backbone. There is an intermolecular C—H⋯N close contact between one of the terminal alkyne groups and one of the N atoms, with a C⋯N distance of 3.374 (3) A. Intermolecular interactions are also present between the alkynyl H atoms and C≡C groups.