136455-49-7Relevant academic research and scientific papers
Tuning Intrinsic and Extrinsic Proton Conduction in Metal-Organic Frameworks by the Lanthanide Contraction
Wong, Norman E.,Ramaswamy, Padmini,Lee, Andrew S.,Gelfand, Benjamin S.,Bladek, Kamila J.,Taylor, Jared M.,Spasyuk, Denis M.,Shimizu, George K.H.
, p. 14676 - 14683 (2017)
Seven isomorphous lanthanide metal-organic frameworks in the PCMOF-5 family, [Ln(H5L)(H2O)n](H2O) (L = 1,2,4,5-tetrakis(phosphonomethyl)benzene, Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) have been synthesized and characterized. This family contains 1-D water-filled channels lined with free hydrogen phosphonate groups and gives a very low activation energy pathway for proton transfer. The lanthanide contraction was employed to systematically vary the unit cell dimensions and tune the proton conducting pathways. LeBail fitting of the crystalline series shows that the crystallographic a-axis, along the channel, can be varied in increments less than 0.02 ? correspondingly shortening the proton transfer pathway. The proton conductivities for the La and Pr complexes were roughly an order of magnitude higher than other members of the series (10-3 S cm-1 versus 10-4 S cm-1). Single crystal structures of the high and low conducting members of the series (La, Pr for high and Ce for low) affirm the structural similarities extend beyond the unit cell parameters to positions of free acid groups and included water molecules. Scanning electron microscopy reveals marked differences in particle size of the different members of the Ln series owing to lattice strain effects induced by changing the lanthanide. Notably, the high conducting La and Pr complexes have the largest particle sizes. This result contradicts any notion that degradation of the MOF at grain boundaries is enabling the observed conductivity as proton conduction dominated by extrinsic pathways would be enabled by small particles (i.e., the La and Pr complexes would be the worst conductors). Proton conductivity measurements of a ball milled sample of the La complex corroborate this result.
Design of Assembled Systems Based on Conjugated Polyphenylene Derivatives and Carbon Nanohorns
Iglesias, Daniel,Guerra, Javier,Gómez, M. Victoria,Rodríguez, Antonio M.,Prieto, Pilar,Vázquez, Ester,Herrero, M. Antonia
, p. 11643 - 11651 (2016)
Promising materials have been designed and fully characterised by an effective interaction between versatile platforms such as carbon nanohorns (CNHs) and conjugated molecules based on thiophene derivatives. Easy and non-aggressive methods have been described for the synthesis and purification of the final systems. Oligothiophenephenylvinylene (OTP) systems with different geometries and electron density are coupled to the CNHs. A wide range of characterization techniques have been used to confirm the effective interaction between the donor (OTP) and the acceptor (CNH) systems. These hybrid materials show potential for integration into solar cell devices. Importantly, surface-enhanced Raman spectroscopy (SERS) effects are observed without the presence of any metal surface in the system. Theoretical calculations have been performed to study the optimised geometries of the noncovalent interaction between the surface and the organic molecule. The calculations allow information on the monoelectronic energies of HOMO–LUMO orbitals and band gap of different donor systems to be extracted.
A water-stable metal-organic framework with highly acidic pores for proton-conducting applications
Taylor, Jared M.,Dawson, Karl W.,Shimizu, George K. H.
, p. 1193 - 1196 (2013)
Metal-organic framework (MOF) materials are a nontraditional route to ion conductors, but their crystallinity can give insight into molecular-level transport mechanisms. However, some MOFs can be structurally compromised in humid environments. A new 3D metal-organic framework, PCMOF-5, is reported which conducts protons above 10-3 S/cm at 60 C and 98% relative humidity. The MOF contains free phosphonic acid groups, shows high humidity stability, and resists swelling in the presence of hydration. Channels filled with crystallographically located water and acidic groups are also observed.
Shedding Light on the Origin of Solid-State Luminescence Enhancement in Butterfly Molecules
Sánchez-Ruiz, Antonio,Rodríguez-López, Julián,Garzón-Ruiz, Andrés,Jiménez-Pulido, Sonia B.,Illán-Cabeza, Nuria A.,Navarro, Amparo,García-Martínez, Joaquín C.
supporting information, p. 13990 - 14001 (2020/10/02)
Different molecular strategies have been carefully evaluated to produce solid-state luminescence enhancement (SLE) in compounds that show dark states in solution. A set of α-phenylstyrylarene derivatives with a butterfly shape have been designed and synthesised, for the first time, with the aim of improving the solid-state fluorescence emission of their parent styrylarene compounds. Although these butterfly molecules are not fluorescent in solution, one of them (1,2,4,5-tetra(α-phenylstyryl)benzene) exhibits a fluorescence quantum yield as high as 68 % in a drop-cast sample and 31 % in its crystalline form. In contrast, 1,3,5-tris(α-phenylstyryl)benzene and 4,6-bis(α-phenylstyryl)pyrimidine do not show SLE. A range of fluorescence spectroscopy experiments and DFT calculations were carried out to unravel the origin of different photophysical behaviour of these compounds in the solid state. The results indicate that a rational strategy to control the SLE effect in luminogens depends on a delicate balance between molecular properties and inter-/intramolecular interactions in the solid state.
Synthesis of rigid π-conjugated mono-, bis-, tris-, and tetrakis(terpyridine)s: Influence of the degree and pattern of substitution on the photophysical Properties
Winter, Andreas,Friebe, Christian,Hager, Martin D.,Schubert, Ulrich S.
supporting information; experimental part, p. 801 - 809 (2009/07/05)
A series of rigid π-conjugated mono-, bis-, tris-, and tetrakis-(terpyridine)s 3-8 was synthesized in high yields by means of Horner-Wadsworth-Emmons (HWE) reactions between benzyl phosphonates 1 and an aldehyde-functionalized ter-pyridine derivative 2. The photophysical properties of the materials in solution and in the solid state depend strongly both on the numbers of terpyridine moieties attached to the central phenyl cores and on the geometries of the compounds. The photophysical behavior of the ortho-substituted compounds 5 and 8 indicated significant changes in the geometries, together with major extensions of the effective π-conjugated systems upon excitation. Bright green emission with high quantum yields was observed for the tetrakis(ter-pyridine) derivative 8.
Luminescent amphiphilic dendrimers with oligo(p-phenylene vinylene) core branches and oligo(ethylene oxide) terminal chains: Syntheses and stimuli-responsive properties
Chang, Dong Wook,Dai, Liming
, p. 364 - 371 (2008/02/03)
A class of new dendrimers consisting of hydrophobic oligo(p-phenylene vinylene) core branches and hydrophilic oligo(ethylene oxide) terminal chains was synthesized. These amphiphilic dendritic molecules are highly luminescent and exhibit critical micellization behaviors. They also show a lower critical solution temperature (LCST) in an aqueous medium. Both the critical micelle concentration (CMC) and LCST increased with increasing branch number and the ratio of the hydrophilic oligo(ethylene oxide) to hydrophobic oligo(p-phenylene vinylene) moieties. Besides, a temperature-dependent phase transition from a clear to cloudy aqueous solution was observed. The temperature-induced phase transition was also reflected by fluorescence quenching, 1H NMR resonance peak broadening, and UV-vis absorption shift arising from the hydrophobic conjugated core. These changes in the phase structure and photophysical properties were demonstrated to be highly reversible, indicating some interesting stimuli-responsive behaviors. The Royal Society of Chemistry.
Bis-, tris-, and tetrakis(squaraines) linked by stilbenoid scaffolds
Gerold, Jürgen,Holzenkamp, Uta,Meier, Herbert
, p. 2757 - 2763 (2007/10/03)
The oligosquaraines 1-5, with stilbenoid scaffolds, were prepared by multistep syntheses in which the final steps consisted of condensation reactions between the semisquaric acid 21 and multiple resorcinols 12b-15b and 17b. The target compounds exhibit in
A new synthetic route to tribenzo[a,e,i][12]annulenes
Meier, Herbert,Fetten, Michael
, p. 1535 - 1538 (2007/10/03)
The tribenzo[a,e,i][12]annulene 10 and the corresponding twofold annulene 14 were prepared on synthetic routes which first led from suitably functionalised starting compounds (2, 11) to the 1,2-distyryl- and 1,2,3,4- tetrastyrylbenzene derivatives 9 and 13 with two and four formyl groups, respectively. The cyclisation to 10 and 14 was achieved by applying the McMurry reaction. The extended ring system of compound 14 represents a discotic mesogen. The generation of liquid crystals was obtained with eight hexyloxy chains on the periphery. (C) 2000 Elsevier Science Ltd.
