John J. Morrison

Synthesis of functionalised porous network silsesquioxane polymers

Porous polyhedral silsesquioxane (POSS)-based network polymers are prepared using hydrosilation copolymerisation reactions of a silyl-functionalised POSS molecule with a vinyl-functionalised moiety. Characterisation of these solids show them to possess pore structures in the mesoporous regime, and polymers with longer organic linking groups showing evidence of flexible wall structures. Functionalisation of the polymers is carried out by reaction with triflic acid or sodium hydroxide, followed by incorporation of CpTiCl3. EXAFS spectroscopy results are consistent with the titanium being coordinated to the oxygen atoms that make up part of a POSS unit.

Preparation of bis(dithienothiophene) derivatives for organic thin film transistors

Abstract The synthesis of two α,α′-disubstituted bis(dithienothiophene) (BDT) derivatives is described. These have been deposited by vacuum sublimation as the active layers in organic thin film transistors (TFTs). The devices exhibit high ON/OFF ratios and preliminary studies show mobilities of 1 X 10−3 and 2 x 10−2 cm2 V−1 s−1 respectively for dithiohexyl (DTH-BDT) and dioctyl (DO-BDT) substituted bis(dithienothiophene). DTH-BDT is found to be considerably more soluble than the unsubstituted BDT.

Synthesis of two new aluminophosphate based layered materials using Tet-A as a structure-directing agent

A layered aluminofluorophosphate and a cobalt–aluminophosphate material have been prepared using the azamacrocycle meso-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane (Tet-A) as a structure-directing agent (SDA). Both were synthesised using hydrothermal techniques and their structures solved using microcrystal X-ray diffraction. The first material, [F, Tet-A]-AlPO-1, has the molecular formula Al10P10O40F2C16N4H38 and crystallises in the orthorhombic space group Pca21. Its inorganic layered structure is related to the AlPO-41 (AFO) zeolite structure type. The second material, [Co, Tet-A]-AlPO-2, has the formula Al4(PO4)4(HPO4)2·[Co(C16N4H36)]·C16N4H38·2H2O and crystallises in the triclinic space group P. This material contains a cobalt–Tet-A complex that is covalently bound to the inorganic framework and an uncoordinated Tet-A molecule that is hydrogen bonded to the framework.

Synthesis of aldehyde functionalised polyhedral oligomeric silsesquioxanes

Hydrosilylation reactions have been used to functionalise the exterior surfaces of octavinyloctasilsesquioxane molecules to provide routes to octaaldehyde molecules. These have been characterised by NMR and MALDI (matrix assisted laser desorption/ionisation)-TOF mass spectroscopy. Further reactions of the molecules to produce carboxylic acid and Schiff base functionalised species are also reported. The effect of temperature and catalyst on the regioselectivity of the reaction is discussed.

Synthesis of thiophene subtituted ruthenium and rhenium bipyridyl complexes.

3-Alkyl thiophenes may be conveniently polymerised by chemical or electrochemical means and further processed to provide electroactive polymers. Here we describe a versatile synthetic strategy that provides thiophene-metal complexes with potential use in the fields of redox active polymers and in electroluminescent devices. The electrochemical behavior of two complexes is established and is reported.

Flash vacuum pyrolysis over magnesium. Part 1. Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides

Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E,E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.

Novel thermal cyclisation of o-methylstyrylalkynes to give 2-alkenylnaphthalenes

Abstract Formation of o -methylstyrylalkynes by flash vacuum pyrolysis of the corresponding stabilised phosphorus ylides at 900 °C is accompanied by unexpected cyclisation to give 2-alkenylnaphthalenes and deuterium labelling has been used to elucidate the mechanisms involved.

Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 6. Pyrolysis of substituted cinnamoyl ylides as a route to conjugated enynes

The substituted cinnamoyl ylides 6 and 7, readily prepared in one step from the quaternary phosphonium salts 8 and cinnamoyl chlorides 9, undergo extrusion of Ph3PO upon FVP to give the 1,3-enynes 12 and 13 in moderate yield. At 500 °C there is little double bond isomerisation, but at 700 °C this does occur to give almost 1:1 mixtures of E and Z isomers. In a few cases, including those with a nitrophenyl group present, the yields are poor or the reactions fail completely. An attempt to improve upon the poor yield of 1-phenylbutenyne by use of an ester stabilised ylide was only partly successful since the severe conditions required for loss of the ester group resulted in significant isomerisation to naphthalene. The fully assigned 13C NMR spectra for 20 enynes are reported. One example of the isomeric β,γ-unsaturated-δ-oxo ylides, 14 has been prepared and is found to undergo loss of Ph3P on FVP at 700 °C to give indene and benzene in low yield.

Flash vacuum pyrolysis of stabilised phosphorus ylides. Part10.1 Generation of 2-methylstyrylalkynes and theirthermal cyclisation to 2-alkenylnaphthalenes

A series of nine 2-methylcinnamoyl phosphorus ylides 7 have been prepared and are found upon FVP at 500 °C to undergo loss of Ph3PO to afford the corresponding styrylalkynes 8 whose fully assigned 13C NMR spectra are presented. FVP of the ylides at 900 °C leads to cyclisation to give substituted naphthalenes 9–18; the mechanism of these reactions may proceed either by initial hydrogen atom loss or an initial [1,7]hydrogen shift, but an alternative route involving an initial [1,3]hydrogen shift has been ruled out by examination of a deuterium labelled analogue. For the α-phenyl ylides 7d and 7i a further cyclisation leads to benzo[c]fluorene derivatives and this process has been extended to a thiophene analogue to give fluoreno[3,4-b]thiophene. The formation of 2-ethylnaphthalene as the main product from the α-methoxycarbonyl ylide 7e is due to a secondary thermal reaction of methyl 2-naphthylacetate which may involve a radical chain reaction featuring, as the propagation step, an unusual homolytic substitution at a methoxy carbon by a 2-naphthylmethyl radical.