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The effect of substituting o‐carborane into the most sterically hindered positions of phenanthrene and benzo(k)tetraphene is reported. Synthesised via a Bull–Hutchings–Quayle benzannulation, the crystal structures of these non‐linear acenes exhibited the highest aromatic deformation parameters observed for any reported carborane compound to date, and among the largest carboranyl C−C bond length of all organo‐substituted o‐carboranes. Photoluminescence studies of these compounds demonstrated efficient intramolecular charge‐transfer, leading to aggregation induced emission properties. Additionally, an unusual low‐energy excimer was observed for the phenanthryl compound. These are two new members of the family of carborane‐functionalised non‐linear acenes, notable for their peculiar structures and multi‐luminescent properties., o ‐Carborane‐functionalised phenanthrene and benzo(k)tetraphene are reported in this work; two highly sterically hindered structures, with the latter displaying the largest aromatic deformation parameters of any organo‐substituted o‐carborane compound, and amongst the longest carboranyl C−C bond. Functionalisation of these polycyclic aromatic hydrocarbons induces stimuli‐responsive luminescence properties, including aggregation‐induced emission.

The requirement to consider the whole lifecycle of products including disassembly and recycling has resulted in considerable interest in debond-on-demand adhesives. These smart materials undergo controlled loss of adhesive strength when subject to a specific stimulus. This paper reports the design of a crosslinked polyurethane (PU) adhesive which incorporates a fluoride responsive degradable group. The crosslinked PU (CLP) adhesive showed a 28 % increase in adhesive bonding strengths by lap shear testing (14.6 MPa) when compared to structurally analogous linear PU (LPU) adhesive (11.4 MPa). After 3 h in contact with fluoride ions, the CLP exhibited a 55 % loss in adhesive bonding strength (from 14.6 MPa to 6.7 MPa) as a consequence of selective degradation of covalent bonds at the crosslinking sites. This work introduces a new route to dismantle components adhered with the widely used PU adhesives, facilitating recovery of valuable materials, and dramatically reducing waste.

The role of the carborane isomer is investigated on the structural and photophysical properties of molecules comprising a carborane cluster and a conjugated organic moiety is investigated by synthesizing isomeric o-, m-, and p-carboranyl-anthracene donor–acceptor dyads. While appending a carborane leads to emission from a low energy intramolecular charge transfer state for the o-isomer, as well as emission from an excited state localized on the anthracene, this is not the case for the m- and p-carborane derivatives. This difference is attributed to a lower electron affinity for the latter two isomers. However, adding both m- and p- deforms the aromatic backbone and increases its structural rigidity, reducing non-radiative decay pathways and hence enhancing photoluminescence quantum efficiency relative to anthracene.

The synthesis of a highly twisted chrysene derivative incorporating two electron deficient o‐carboranyl groups is reported. The molecule exhibits a complex, excitation‐dependent photoluminescence, including aggregation‐induced emission (AIE) with good quantum efficiency and an exceptionally long singlet excited state lifetime. Through a combination of detailed optical studies and theoretical calculations, the excited state species are identified, including an unusual excimer induced by the presence of o‐carborane. This is the first time that o‐carborane has been shown to induce excimer formation ab initio, as well as the first observation of excimer emission by a chrysene‐based small molecule in solution. Bis‐o‐carboranyl chrysene is thus an initial member of a new family of o‐carboranyl phenacenes exhibiting a novel architecture for highly‐efficient multi‐luminescent fluorophores.

This paper reports the solvent-free synthesis of a series of six fluoride responsive debond-on-demand polyurethane (PU) adhesives that contain a silyl functionalised degradable unit (DU). To optimise the adhesion strength and debonding nature of the adhesives, the chemical composition of the PUs was varied according to the structure of the polyol or the diisocyanate component in the polymer mainchain. 1H NMR spectroscopy was used to study the depolymerisation behaviour in solution state. It showed that tetra-butylammonium fluoride (TBAF) triggered the breakdown of the DU unit without fragmenting the polyol mainchain indiscriminately. On exposure to fluoride ions, the PUs underwent depolymerisation with reductions in Mn ranging from 64 to 90% as measured by GPC analysis. The morphology and thermal properties of the PUs were characterised by differential scanning calorimetry (DSC), rheology and variable temperature (VT) SAXS/WAXS analysis. Each technique demonstrated the reversibility of the supramolecular polymer network under thermal stimuli. PUs containing poly(butadiene) soft segments were amorphous with glass transition and viscoelastic transition temperatures dependent on the nature of the soft segment and diisocyanate starting materials. The PU containing a polyester soft segment exhibited a defined melting point at 49 °C. Mechanical stress-strain analysis of the series of PUs showed each exhibited greater than 70% reduction in toughness after treatment with TBAF for 30 min as a consequence of the chemo-responsive degradation of the polymer mainchain. The material featuring an ester-based polyol demonstrated excellent adhesion at bonding temperatures as low as 60 °C. Moreover, this material could be thermally rebonded if broken by force without loss in adhesion strength over three debond-rebond cycles. Lap shear adhesion tests showed a reduction in adhesive strength of approximately 40% (from 11.4 MPa to 7.3 MPa) on exposure to fluoride ions.

We report the one-pot, solvent free synthesis of a stimuli-responsive polyurethane (PU) adhesive. The hard domains within the supramolecular PU network contain a silyl protected phenol ‘degradable unit’ (DU). The DU undergoes rapid decomposition (

In this review we aim to provide an introductory guide to blocked isocyanates, through discussion on different examples of blocking groups, along with experimental considerations for their application. The review brings together updated examples of functionalities used and places specific emphasis on the analytical techniques used for the determination of deblocking temperature, updating previous reviews with the newly applied technique of X-ray photoelectron spectroscopy (XPS). Additionally, we put forward a brief update on the use of blocked isocyanates for other non-traditional polyurethane based polymer applications. We also highlight the importance of matching the analytical technique to the application of the blocked isocyanate, with differences in material state and experimental parameters having a great impact on the deblocking temperature reported.\ud \ud

A neutral redox-active receptor (ferrocene functionalized calix[4]pyrrole) was used as an active component in carbon paste electrodes and ion-selective electrodes ISEs, for the detection of anions in aqueous solution. Measurements with the carbon paste electrodes were conducted using Osteryoung square-wave voltammetry. At the surface of the modified electrode the redox potential of ferrocene-substituted calix[4]pyrrole was found to be at ca. 400 mV. Amongst the anions studied, dihydrogen phosphate and fluoride caused the strongest decrease of peak current (approximately 25%), followed by bromide and chloride. This sensitivity sequence was compared with that obtained with ISEs containing the ferrocene-substituted calix[4]pyrrole. The influence of the interface between host molecule environment and aqueous solution containing target anion on the molecular recognition process and electrochemical signal generation has been investigated.

A variety of furan and thiophene amide and thioamide cleft type anion receptors have been synthesised and crystallographically characterised. Unlike 2,5-diamidopyrrole anions, analogous 2,5-diamidofurans and thiophenes do not interlock in the solid state. The anion binding properties of these receptors have been investigated in DMSO/0.5% water solution using 1H NMR titration techniques. Solution studies and solid-state evidence suggests that the thiophene receptors may utilise a thiophene CH hydrogen atom for hydrogen bond formation to anions with a 2,4-diamidothiophene showing similar anion binding affinities to a 2,5-diamidopyrrole.

Thiophene-2,4- and -2,5-biscarboxamides have been synthesised and shown to act as anion receptors in DMSO-d6/water solution. The crystal structure of the fluoride complex of a N,N'-diphenylthiophene-2,5-biscarboxamide derivative has been solved and reveals the involvement of the thiophene CH protons in anion complexation in the solid state.

Four amido-pyrrole cleft anion receptors bearing one or two ferrocene reporter groups have been synthesised and crystallographically characterised. The receptors contain either a non-conjugated (1 and 3) or conjugated (2 and 4) link between the anion binding amido-pyrrole unit and the ferrocene reporter groups. The anion binding affinities and electrochemical behaviour of the receptors in the absence and presence of anions have been studied by 1H NMR titration techniques and cyclic voltammetry using a Pt microdisc working electrode, respectively.

A new calix[4]pyrrole 1 containing a ferrocene moiety attached to one of the meso-positions has been synthesised by co-condensation of pyrrole, cyclohexanone and acetylferrocene. The crystal structure of 1 has been elucidated whilst 1H NMR titration studies in acetonitrile-d3/DMSO-d6 9:1 v/v have revealed that 1 binds fluoride, chloride, and dihydrogen phosphate in this solvent mixture. Electrochemical studies using cyclic voltammetric and square-wave voltammetric techniques show cathodic shifts of up to 100 mV (approx.) with dihydrogen phosphate anions.

3,4-Diphenylfuran-2,5-dicarboxylic acid bis-N-phenylamide 1 and 3,4-biphenyl-furan-2,5-dicarboxylic acid bis-N-butylamide 2 have been synthesised and shown to act as fluoride selective anion receptors in DMSO-d6/0.5% water solution.

Two amido-pyrrole cleft anion receptors bearing two ferrocene reporter groups have been synthesised and crystallographically characterised; the receptors contain either a non-conjugated or conjugated link between the anion-binding amido-pyrrole unit and the ferrocene reporter groups. The anion binding affinities and electrochemical behaviour of the receptors in the absence and presence of anions have been studied by 1H NMR titration techniques and cyclic voltammetry using a Pt microdisc working electrode, respectively.

Metal complexes of 2,5-dicarboxamidopyrroles and 2,5-dicarbothioamidopyrroles have been structurally characterised for the first time, complementing the significant amount of work that has been reported for the analogous pyridine ligands. N,N′-Bis(3,5-dinitrophenyl)-3,4-diphenyl-1H-pyrrole-2,5-dicarboxamide forms octahedral bis(tridentate) complexes with cobalt(III) and nickel(II), where the ligands are bound to the metal centres through deprotonated pyrrole and amide N atoms. N,N′-Dibutyl-3,4-diphenyl-1H-pyrrole-2,5-dicarboxthioamide and N,N′-diphenyl-3,4-diphenyl-1H-pyrrole-2,5-dicarboxthioamide also form bis(tridentate) cobalt complexes but are only deprotonated at the pyrrole N atom, the remainder of the coordination sphere comprising the thioamide S atoms. The dibutyl derivative was isolated as a Co(II) complex, whereas the diphenyl system deposited a Co(III) complex. In contrast, N,N′-dibutyl-3,4-dichloro-1H-pyrrole-2,5-dicarboxamide was found to act as a bidentate ligand, in an octahedral cobalt(II) complex comprising of two bidentate pyrrole ligands, and two aqua ligands. Synthesis of N,N-bis(pyridin-2-ylmethyl)-3,4-diphenyl-1H-pyrrole-2,5-carboxamide gave a pyrrole ligand with increased denticity. Reaction with cobalt(II) chloride resulted in the isolation of a dinuclear helicate complex. The ligand was found to have undergone addition of a methoxy group to one of the linking methylene carbons, presumably as a result of the oxidative addition of solvent methanol.

A new calix[4]pyrrole has been synthesised that contains a 3,4,5-trisbromopyrrole appended to a meso-position which shows enhanced anion affinity as compared to the parent meso-octamethylcalix[4]pyrrole macrocycle.

A new calix[4]pyrrole has been synthesised that contains a 3,4,5-trisbromopyrrole appended to a meso-position which shows enhanced anion affinity as compared to the parent meso-octamethylcalix[4]pyrrole macrocycle.

The title structure, C20H18O8.1.5C(6)H(6), is a tetrasubstituted biphenyl which has a pseudo-inversion centre between the two halves. The benzene solvent molecules lie in special positions, one with twofold rotation symmetry and two with inversion symmetry. The tetramethyl ester molecule is twisted and forms a supramolecular assembly of stacked sheets.

A new calix[4]pyrrole has been synthesised that contains a 3,4,5-trisbromopyrrole appended to a meso-position which shows enhanced anion affinity as compared to the parent meso-octamethylcalix[4]pyrrole macrocycle.