Simon Mathew

Ruthenium Porphyrin Functionalized Single-Walled Carbon Nanotube Arrays-A Step Toward Light Harvesting Antenna and Multibit Information Storage

Ruthenium porphyrin functionalized single-walled carbon nanotube arrays have been prepared using coordination of the axial position of the metal ion onto 4-aminopyridine preassembled single-walled carbon nanotubes directly anchored to a silicon(100) surface (SWCNTs-Si). The formation of these ruthenium porphyrin functionalized single-walled carbon nanotube array electrodes (RuTPP-SWCNTs-Si) has been monitored using infrared spectroscopy (IR), differential pulse voltammetry (DPV), atomic force microscopy (AFM), laser desorption time-of-flight mass spectroscopy (LDI-TOF-MS), UV-vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry. Electrochemical results show two successive one-electron reversible redox waves. The surface concentration of the ruthenium porphyrin molecules is 3.44 x 10 (-8) mol cm (-2). Optical results indicate that the immobilization of ruthenium porphyrin enhances the light absorption of SWCNTs-Si surfaces in the visible light region. Moreover mixed assembly of ferrocene/porphyrin onto carbon nanotube arrays has been achieved by altering the ratio of two redox-active species in the deposition solution. These results suggest the ruthenium porphyrin modified electrodes are excellent candidates for molecular memory devices and light harvesting antennae.

Towards Compatibility between Ruthenium Sensitizers and Cobalt Electrolytes in Dye‐Sensitized Solar Cells

This tuning minimizes energy losses in the device byoptimizingthedrivingforceforregeneration,whichallowsforconsiderableimprovementoftheopen-circuitvoltagerelativeto iodine electrolytes.Current ruthenium(II) sensitizers are not designed toperform with cobalt electrolytes. Among the few examplesreported in the literature,

Tunable, strongly-donating perylene photosensitizers for dye-sensitized solar cells

Broadly absorbing perylene dyes bearing three-triarylamine groups were synthesized via Sonogashira coupling. The triarylamine moieties allowed further installation of electron donating ability, to enable tuning of the oxidation potential and optical band gap. With introducing more electron-donating groups into the three-triarylamine moieties the device performance was improved. The trend can be rationalized by the distribution of the electron density in the HOMO of the perylene moiety as well as the light-harvesting property of the perylene dyes.

Density Gradation of Open Metal Sites in the Mesospace of Porous Coordination Polymers

The prevalence of the condensed phase, interpenetration, and fragility of mesoporous coordination polymers (meso-PCPs) featuring dense open metal sites (OMSs) place strict limitations on their preparation, as revealed by experimental and theoretical reticular chemistry investigations. Herein, we propose a rational design of stabilized high-porosity meso-PCPs, employing a low-symmetry ligand in combination with the shortest linker, formic acid. The resulting dimeric clusters (PCP-31 and PCP-32) exhibit high surface areas, ultrahigh porosities, and high OMS densities (3.76 and 3.29 mmol g-1, respectively), enabling highly selective and effective separation of C2H2 from C2H2/CO2 mixtures at 298 K, as verified by binding energy (BE) and electrostatic potentials (ESP) calculations.

Synthesis, characterization and ab initio investigation of a panchromatic ullazine–porphyrin photosensitizer for dye-sensitized solar cells

An ullazine unit was employed as a donor moiety in a donor–π–acceptor (D–π–A) motif, employing the porphyrin macrocycle as a π-system. Synthesis of this ullazine–porphyrin dyad containing sensitizer (SM63) was achieved and an investigation of the electrochemical and spectroscopic properties of this dye was performed. Introduction of the ullazine donor promoted significant enhancements in long and visible wavelength absorption, leading to panchromatic light harvesting. SM63 demonstrated a maximum absorption approaching 750 nm, a significant improvement compared to the model compound LD14-C8, which features a simpler donor component (4-(N,N-dimethylamino)phenyl) and an absorption onset at ∼700 nm. The dye SM63 was subjected to a rigorous ab initio investigation to gain further insight into its unique absorption and emission properties. Application of the molecular ullazine–porphyrin dyad SM63 into dye-sensitized solar cells afforded a device with significantly improved light harvesting abilities in both the visible region of the spectrum as well as NIR light (∼800 nm), demonstrating the value of ullazine unit in developing panchromatic dyes for light harvesting applications.

Exclusive Photothermal Heat Generation by a Gadolinium Bis(naphthalocyanine) Complex and Inclusion into Modified High-Density Lipoprotein Nanocarriers for Therapeutic Applications

A hydrophobic gadolinium bis(naphthalocyanine) sandwich complex (GdSand) possessing several absorbances across visible and infrared wavelengths (up to 2500 nm) was solubilized in aqueous solution by uptake into a nascent mutant high-density lipoprotein (HDL) nanocarrier. The HDL nanocarrier was additionally functionalized with a trans-activator of transcription peptide sequence to promote efficient cell penetration of the drug delivery system (cpHDL). The dye-loaded nanocarrier (GdSand@cpHDL) exhibited photothermal heat generation properties upon irradiation with near-infrared (NIR) laser light, with controllable heat generation abilities as a function of the incident laser light power. Comparison of the photothermal behavior of the dyes GdSand and the well-explored molecular photothermal agent indocyanine green (ICG) in the cpHDL nanocarrier (i.e., ICG@cpHDL) revealed two significant advantages of GdSand@cpHDL: (1) the ability to maintain elevated temperatures upon light absorption for extended periods of time, with a reduced degree of self-destruction of the dye, and (2) exclusive photothermal heat generation with no detectable singlet oxygen production leading to improved integrity of the cpHDL nanocarrier after irradiation. Finally, GdSand@cpHDL was successfully subjected to an in vitro study against NCI-H460 human lung cancer cells, demonstrating the proof-of-principle utility of lanthanide sandwich complexes in photothermal therapeutic applications.

Surface functionalization of high free-volume polymers as a route to efficient hydrogen separation membranes

There is a sparcity of polymeric membranes with sufficient selectivity for efficient hydrogen separation from syn-gas products, primarily carbon dioxide. Despite hydrogens significantly smaller kinetic diameter, low selectivity arises as other gases are generally more condensable within typical polymeric membranes. Here we report an in situ-controllable, surface polymerization of polydopamine (PDA) and polyaniline (PANI) on high free-volume glassy polymer films, specifically the well studied polymer of intrinsic microporosity (PIM-1) and poly(1-trimethylsilyl-1-propyne) (PTMSP). The resulting nanolayer composite membranes demonstrate a remarkable hydrogen selectivity against N2, CH4 and CO2 (H2/CO2 ∼ 50). The PDA or PANI layers principally serve to increase the diffusive selectivity towards hydrogen whilst the high free volume supports of PIM-1 or PTMSP provide a highly permeable interface for defect-free growth of the selective layer. Whilst both PANI and PDA are effective, these selective layers were found to grow by heterogeneous or homogeneous modes respectively.

Dye-sensitized solar cells using cobalt electrolytes: the influence of porosity and pore size to achieve high-efficiency

Diffusion impediments in redox shuttles are a major limitation to realizing high power conversion efficiencies (PCEs) in dye sensitized solar cells (DSCs) using cobalt complexes. Mass transport limitations are strongly dependent on the pore size and the porosity of mesoporous TiO2 films. Herein, we examine the major factors responsible for mass transport limitations and identify ways to minimize them, achieving highly efficient cobalt based DSCs. Depending on the electrolyte and dye used, the pore size and the porosity of the TiO2 films must be modulated to facilitate diffusion of cobalt complexes through pores. The influence of porosity, pore size and viscosity of the electrolyte used on the performance of DSCs with different maximum obtainable JSCs are studied in detail. These effects were studied using two dye solutions, Y123 (0.2 mM) and a cocktail solution of SM342/Y123 (0.2 mM each, 7 : 1). The JSC is affected primarily by lowered pore sizes as a result of the TiCl4 post-treatment. Transient photocurrent decay measurements were performed on devices featuring photoanodes fabricated with differing porosities and pore sizes. This study indicates that in cells featuring only Y123, recombination rates decreased with decreasing porosity of TiO2 films (i.e. higher TiCl4 concentrations used in their post-treatment). Conversely, in DSCs fabricated with the SM342/Y123 dye cocktail, an intermediate TiCl4 post-treatment concentration (20 mM) afforded the lowest recombination rate, resulting in the preservation of a high open-circuit potential (VOC). It was found that this intermediate concentration regime is optimal in order to achieve an efficiency of over 12.7% at full sun intensity with the SM342/Y123 dye cocktail. Finally, it was concluded that the porosity and pore size must be modulated for different dyes and electrolytes to minimize diffusion limitations of the redox species.

The Synthesis and Characterisation of a Free‐Base Porphyrin–Perylene Dyad that Exhibits Electronic Coupling in Both the Ground and Excited States

A covalent dyad composed of a free-base porphyrin and a perylene diimide (1) was synthesised and characterised by NMR, HRMS, UV/Vis and fluorometric methods. UV/Vis spectrophotometric analysis indicated a moderate coupling between the components in the ground state. Fluorescence spectroscopy revealed that the emissive properties of the dyad showed that the quantum yield of emission from the porphyrin Soret band increased dramatically and could not be rationalised by a straightforward photoinduced energy (and/or electron) transfer, but rather a coupling of excited states.

Finely Controlled Stepwise Engineering of Pore Environments and Mechanistic Elucidation of Water-Stable, Flexible 2D Porous Coordination Polymers

Two porous coordination polymers (PCPs) with different topologies (NTU-19: sql and NTU-20: dia) underwent finely controlled, stepwise crystal conversions to yield a common water-stable, flexible 2D framework (NTU-22: kgm). The crystal conversions occurred directly at higher temperature via the 3D intermediate (NTU-21: nbo), which could be observed at lower temperature. The successful isolation of the intermediate product of NTU-21, characterization with in situ PXRD and UV/Vis spectra were combined with DFT calculations to allow an understanding of the dynamic processes at the atomic level. Remarkably, breakthrough experiments demonstrate NTU-22 with integral structural properties allowed significant CO2 /CH4 mixture separation.