47 results on '"CHAMBRIER, I."'
Search Results
2. Channel length-dependent characterisations of organic thin-film transistors with solution processable gadolinium phthalocyanine derivatives
- Author
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Barard, Seema, primary, Mukherjee, Debdyuti, additional, Sarkar, Sujoy, additional, Kreouzis, T., additional, Chambrier, I., additional, Cammidge, A. N., additional, and Ray, A. K., additional
- Published
- 2019
- Full Text
- View/download PDF
3. Orientation of substituted phthalocyanines on polycrystalline gold: distinguishing between the first layers and thin films
- Author
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Peisert, H., Biswas, I., Zhang, L., Knupfer, M., Hanack, M., Dini, D., Cook, M.J., Chambrier, I., Schmidt, T., Batchelor, D., and Chassé, T.
- Published
- 2005
- Full Text
- View/download PDF
4. Impedance spectroscopic studies on hybrid nanocomposites of lead sulphide Quantum Dots in Solution Processed Phthalocyanine Films
- Author
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Khozaee, Z, Chambrier, I, Sosa Vargas, L, Cammidge, A, and Ray, AK
- Subjects
Nanocomposite ,discotic ,quantum dots ,octahexylphthalocyanine ,macrocyclic - Published
- 2019
5. Influence of the alkyl-chains length on the electronic structure and interface properties of 1,4-octasubstituted zinc phthalocyanines on gold.
- Author
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Dick, S., Peisert, H., Dini, D., Hanack, M., Cook, M. J., Chambrier, I., and Chassé, T.
- Subjects
PHTHALOCYANINES ,PIGMENTS ,ELECTRON emission ,PHOTOEMISSION ,ELECTRONIC structure ,SPECTRUM analysis - Abstract
We compare the interface properties of various 1,4,8,11,15,18,22,25 octa-alkyl-substituted zinc phthalocyanines [(But)
8 PcZn, (Hep)8 PcZn, (Dec)8 PcZn] with those of unsubstituted zinc phthalocyanine (PcZn) on gold using x-ray photoemission spectroscopy and valence band ultraviolet photoemission spectroscopy. Although the separation between the aromatic cores in the evaporated thin films depends clearly on the alkyl-chain length, it is found that the nature of the substituents causes only minor changes of electronic properties, such as optical gap and ionization potential. It is shown that the observed small energetic shifts for film thicknesses larger than the molecule size cannot be understood in terms of a band bending like mechanism. [ABSTRACT FROM AUTHOR]- Published
- 2005
- Full Text
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6. A tetrabenzotriazaporphyrin based organic thin film transistor: Comparison with a device of the phthalocyanine analogue
- Author
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Chaure, NB, Cammidge, AN, Chambrier, I, Cook, MJ, and Ray, AK
- Abstract
The characteristics of bottom-gate bottom-contact organic thin film field-effect transistors (OTFTs) with 70 nm thick films of solution processed non-peripherally octahexyl-substituted nickel tetrabenzo triazaporphyrin (6NiTBTAP) molecules as active layers on silicon substrates are experimentally studied and the results are compared with the similary configured transistors using the corresponding nickel phthalocyanine (6NiPc) compound. 6NiTBTAP transistors are found to exhibit improved performance over 6NiPc transistors in terms of greater saturation hole mobility, two orders of magnitude higher on/off ratio and lower threshold voltage. This enhanced performance of 6NiTBTAP OTFTs over 6NiPc devices is attributed to improved surface morphology and large grain size of the active 6NiTBTAP film.
- Published
- 2015
7. ChemInform Abstract: Reaction of Phthalonitrile with Alkoxide Ions.
- Author
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CHAMBRIER, I., primary and COOK, M. J., additional
- Published
- 2010
- Full Text
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8. ChemInform Abstract: Synthesis and Characterization of Functionalized Phthalocyanine Compounds for Fabrication of Self-Assembled Monolayers
- Author
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CHAMBRIER, I., primary, COOK, M. J., additional, and RUSSELL, D. A., additional
- Published
- 2010
- Full Text
- View/download PDF
9. Molecular Order within Langmuir−Blodgett Films of Two Amphiphilic Octasubstituted Phthalocyanines Studied by Atomic Force Microscopy
- Author
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Vélez, M., primary, Vieira, S., additional, Chambrier, I., additional, and Cook, M. J., additional
- Published
- 1998
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10. Formation and characterisation of a self-assembled phthalocyanine monolayer suitable for gas sensing
- Author
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Simpson, T.R.E., primary, Russell, D.A., additional, Chambrier, I., additional, Cook, M.J., additional, Horn, A.B., additional, and Thorpe, S.C., additional
- Published
- 1995
- Full Text
- View/download PDF
11. Langmuir-Blodgett films of an asymmetrically substitute phthalocyanine
- Author
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Crouch, D., primary, Thorpe, S.C., additional, Cook, M.J., additional, and Chambrier, I., additional
- Published
- 1994
- Full Text
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12. ChemInform Abstract: Synthesis and Characterization of Some 1,4,8,11,15,18,22,25-Octaalkyl- and 1,4,8,11,15,18-Hexaalkyl-22,25-bis(carboxypropyl)phthalocyanines.
- Author
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MCKEOWN, N. B., primary, CHAMBRIER, I., additional, and COOK, M. J., additional
- Published
- 1990
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- View/download PDF
13. Generation of Cytotoxic Singlet Oxygen via Phthalocyanine-Stabilized Gold Nanoparticles: A Potential Delivery Vehicle for Photodynamic Therapy
- Author
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Hone, D. C., Walker, P. I., Evans-Gowing, R., FitzGerald, S., Beeby, A., Chambrier, I., Cook, M. J., and Russell, D. A.
- Abstract
Gold nanoparticles have been stabilized with a phthalocyanine (Pc) photosensitizer. Transmission electron microscopy confirmed that the coated particles were in the 2−4 nm size regime. Energy-dispersive X-ray analysis revealed that the Pc macrocycle was present on the gold surface and also that the TOAB phase transfer reagent, used during the synthesis, was associated with the nanoparticles. The three-component (photosensitizer/gold/phase transfer reagent) nanoparticles were shown to generate singlet oxygen with enhanced quantum yields as compared to the free Pc. Additionally, the association of the transfer reagent promoted the solubility of the surface-bound hydrophobic sensitizer in polar solvents which would facilitate their systemic injection. The results suggest that these three-component structures have potential as a useful vehicle for the delivery of photosensitizer agents in photodynamic therapy.
- Published
- 2002
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14. ChemInform Abstract: Reaction of Phthalonitrile with Alkoxide Ions.
- Author
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CHAMBRIER, I. and COOK, M. J.
- Published
- 1991
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- View/download PDF
15. ChemInform Abstract: Synthesis and Characterization of Functionalized Phthalocyanine Compounds for Fabrication of Self-Assembled Monolayers.
- Author
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CHAMBRIER, I., COOK, M. J., and RUSSELL, D. A.
- Published
- 1996
- Full Text
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16. The in vivo efficacy of phthalocyanine-nanoparticle conjugates for the photodynamic therapy of amelanotic melanoma.
- Author
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Camerin M, Magaraggia M, Soncin M, Jori G, Moreno M, Chambrier I, Cook MJ, and Russell DA
- Abstract
The efficiency of a Zn(II)-phthalocyanine disulphide (C11Pc), a compound with both phthalocyanine units bearing seven hexyl chains and a sulphur terminated C11 chain, as a photodynamic therapy (PDT) agent was investigated in C57 mice bearing a sub-cutaneously transplanted amelanotic melanoma. The phthalocyanine was intravenously injected at a dose of 1.5 micromol/kg body weight either free or bound to gold nanoparticles, using a Cremophor emulsion as a delivery vehicle. Biodistribution studies at selected post-injection times showed that the nanoparticle-associated C11Pc was recovered in significantly larger amounts from all the examined tissues and the serum and yielded a greater selectivity of tumour targeting: thus, the ratio between the amount of phthalocyanine recovered from the amelanotic melanoma and the skin (peritumoural tissue) increased from 2.3 to 5.5 from the free to the gold nanoparticle-bound C11Pc at 24 h after injection. PDT studies with the C11Pc-loaded amelanotic melanoma showed a markedly more significant response of the tumour in the mice that had received the nanoparticle-bound photosensitiser; the PDT effect was especially extensive if the irradiation was performed at 3h after C11Pc injection when large phthalocyanine amounts were still present in the serum. This suggests that the PDT promoted by C11Pc predominantly acts via vascular damage at least in this specific animal model. This hypothesis was fully confirmed by electron microscopy observations of tumour specimens obtained at different times after the end of PDT, showing an extensive damage of the blood capillaries and the endothelial cells. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
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17. Formation of Gold(III) Alkyls from Gold Alkoxide Complexes
- Author
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Manfred Bochmann, Isabelle Chambrier, David L. Hughes, Julio Fernandez-Cestau, Dragoş-Adrian Roşca, Peter H. M. Budzelaar, Chambrier, I., Roşca, D., Fernandez Cestau, J., Hughes, D. L., Budzelaar, Petrus Henricus Maria, and Bochmann, M.
- Subjects
Tris ,Period (periodic table) ,010405 organic chemistry ,Chemistry ,Stereochemistry ,Radical ,Organic Chemistry ,Methoxide ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Phosphorane ,Article ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Alkoxide ,Physical and Theoretical Chemistry ,Benzene ,Phosphine - Abstract
The gold(III) methoxide complex (C∧N∧C)AuOMe (1) reacts with tris(p-tolyl)phosphine in benzene at room temperature under O abstraction to give the methylgold product (C∧N∧C)AuMe (2) together with OP(p-tol)3 ((C∧N∧C) = [2,6-(C6H3tBu-4)2pyridine]2−). Calculations show that this reaction is energetically favorable (ΔG = −32.3 kcal mol−1). The side products in this reaction, the Au(II) complex [Au(C∧N∧C)]2 (3) and the phosphorane (p-tol)3P(OMe)2, suggest that at least two reaction pathways may operate, including one involving (C∧N∧C)Au• radicals. Attempts to model the reaction by DFT methods showed that PPh3 can approach 1 to give a near-linear Au−O−P arrangement, without phosphine coordination to gold. The analogous reaction of (C∧N∧C)AuOEt, on the other hand, gives exclusively a mixture of 3 and (p-tol)3P(OEt)2. Whereas the reaction of (C∧N∧C)AuOR (R = But, p-C6H4F) with P(p-tol)3 proceeds over a period of hours, compounds with R = CH2CF3, CH(CF3)2 react almost instantaneously, to give 3 and OP(ptol) 3. In chlorinated solvents, treatment of the alkoxides (C∧N∧C)AuOR with phosphines generates [(C∧N∧C)Au(PR3)]Cl, via Cl abstraction from the solvent. Attempts to extend the synthesis of gold(III) alkoxides to allyl alcohols were unsuccessful; the reaction of (C∧N∧C)AuOH with an excess of CH2 CHCH2OH in toluene led instead to allyl alcohol isomerization to give a mixture of gold alkyls, (C∧N∧C)AuR′ (R′ = −CH2CH2CHO (10), −CH2CH(CH2OH)OCH2CHCH2 (11)), while 2-methallyl alcohol affords R′ = CH2CH(Me)CHO (12). The crystal structure of 11 was determined. The formation of Au−C instead of the expected Au−O products is in line with the trend in metal−ligand bond dissociation energies for Au(III): M−H > M−C > M−O.
- Published
- 2017
18. Thermally stable gold(III) alkene and alkyne complexes: Synthesis, structures, and assessment of the trans‐influence on gold‐ligand bond enthalpies
- Author
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Manfred Bochmann, David L. Hughes, Peter M. H. Budzelaar, Luca Rocchigiani, Isabelle Chambrier, Chambrier, I., Rocchigiani, L., Hughes, D. L., Budzelaar, P. H. M., and Bochmann, M.
- Subjects
Trans effect ,Norbornadiene ,Alkyne complexes ,Alkyne ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Catalysis ,Alkene complexes ,chemistry.chemical_compound ,Dibenzylideneacetone ,Bond energy ,chemistry.chemical_classification ,010405 organic chemistry ,Ligand ,Alkene ,Chemistry (all) ,Organic Chemistry ,General Chemistry ,0104 chemical sciences ,Density functional calculations ,Alkene complexe ,chemistry ,Acetylene ,Gold ,Density functional calculation ,Alkyne complexe - Abstract
The reaction of [C^C)Au(OEt2 )2 ]+ with 1,5-cyclooctadiene or norbornadiene affords the corresponding olefin complexes [(C^C)Au(COD)]SbF6 and [(C^C)Au(NBD)]SbF6 , which are thermally stable in solution and the solid state (C^C=4,4'-di-tert-butylbiphenyl-2,2'-diyl). The crystal structures of these complexes have been determined. By contrast, dienones such as dibenzylideneacetone are O- rather than C=C-bonded. The reactions of (C^C)Au(OAcF )(L) (L=PMe3 or CNxyl) with B(C6 F5 )3 in the presence of bis(1-adamantyl)acetylene give the mixed-ligand alkyne complexes [(C^C)Au(AdC≡CAd)(L)]+ , the first complexes of their type in gold chemistry. In the presence of an excess of acetylene these compounds are thermally stable in solution and as solids. The bonding of n- and π-donor ligands to AuIII fragments and the effect of the trans influence exerted by N- and C-donors was explored with the aid of DFT calculations. Results show that the Au-L bond enthalpies trans to anionic C are 35-60 % of the enthalpies trans to N, with strong π-acceptors being particularly affected. In comparison with [Me2 Au]+ , the [(C^C)Au]+ fragment is more polar and in bond enthalpy terms resembles Me2 Pt.
- Published
- 2018
19. Scramble-Free Synthesis of Unhindered trans -A 2 B 2 -Mesoaryl Porphyrins via Bromophenyl Dipyrromethanes.
- Author
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Alshammari MH, Alhunayhin SMN, Hughes DL, Chambrier I, and Cammidge AN
- Abstract
Trans -disubstituted porphyrins are highly valuable intermediates across diverse fields, but they pose a significant synthesis challenge in some cases due to scrambling and formation of complex mixtures. Conditions that minimize scrambling also lower yields, but steric hindrance around the meso-aryl substituent can effectively suppress scrambling altogether. Here we report a straightforward approach to valuable trans-A
2 B2 porphyrin intermediates that are otherwise very difficult to obtain, through use of removable blocking bromide substituents.- Published
- 2024
- Full Text
- View/download PDF
20. Luminescent Au(III)-M(I) (M = Cu, Ag) Aggregates Based on Dicyclometalated Bis(alkynyl) Gold Anions†.
- Author
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Lara Garnica R, Rama RJ, Chambrier I, Agonigi G, Hughes DL, Lalinde E, Bochmann M, and Fernandez-Cestau J
- Abstract
The syntheses and structures of a series of complexes based on the C
∧ C-chelated Au(III) unit (C∧ C = 4,4'-bis( t -butyl) 2,2'-biphenyl-1,1'-diyl) are reported, namely, [{(C∧ C)Au(C≡Ct Bu)2 }2 M2 ], (C∧ C)Au(C≡CR)(C≡NXyl), and [{(C∧ C)Au(C≡CR)2 }{M(C≡NXyl)}] (M = Ag, Cu; R =t Bu, C6 H4 t Bu-4, C6 H4 OMe-4; Xyl = 3,5-Me2 C6 ). The X-ray structures reveal a broad range of dispositions determined by the different coordination modes of Ag(I) or Cu(I). The complexes are bright photoemitters in the solid state and in poly(methyl methacrylate) (PMMA) films. The photoluminescence is dominated by3 ). The X-ray structures reveal a broad range of dispositions determined by the different coordination modes of Ag(I) or Cu(I). The complexes are bright photoemitters in the solid state and in poly(methyl methacrylate) (PMMA) films. The photoluminescence is dominated by3 IL(C∧ C) transitions, with indirect effects from the rest of the molecules, as supported by theoretical calculations. This work opens up the possibility of accessing Au(III) carbon-rich anions to construct photoluminescent aggregates.- Published
- 2023
- Full Text
- View/download PDF
21. Protomers of the green and cyan fluorescent protein chromophores investigated using action spectroscopy.
- Author
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Ashworth EK, Dezalay J, Ryan CRM, Ieritano C, Hopkins WS, Chambrier I, Cammidge AN, Stockett MH, Noble JA, and Bull JN
- Subjects
- Spectrum Analysis, Green Fluorescent Proteins chemistry, Ions chemistry, Protein Subunits chemistry
- Abstract
The photophysics of biochromophore ions often depends on the isomeric or protomeric distribution, yet this distribution, and the individual isomer contributions to an action spectrum, can be difficult to quantify. Here, we use two separate photodissociation action spectroscopy instruments to record electronic spectra for protonated forms of the green ( p HBDI
+ ) and cyan (Cyan+ ) fluorescent protein chromophores. One instrument allows for cryogenic ( T = 40 ± 10 K) cooling of the ions, while the other offers the ability to perform protomer-selective photodissociation spectroscopy. We show that both chromophores are generated as two protomers when using electrospray ionisation, and that the protomers have partially overlapping absorption profiles associated with the S1 ← S0 transition. The action spectra for both species span the 340-460 nm range, although the spectral onset for the p HBDI+ protomer with the proton residing on the carbonyl oxygen is red-shifted by ≈40 nm relative to the lower-energy imine protomer. Similarly, the imine and carbonyl protomers are the lowest energy forms of Cyan+ , with the main band for the carbonyl protomer red-shifted by ≈60 nm relative to the lower-energy imine protomer. The present strategy for investigating protomers can be applied to a wide range of other biochromophore ions.- Published
- 2023
- Full Text
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22. Complementary Syntheses Giving Access to a Full Suite of Differentially Substituted Phthalocyanine-Porphyrin Hybrids.
- Author
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Alkorbi F, Díaz-Moscoso A, Gretton J, Chambrier I, Tizzard GJ, Coles SJ, Hughes DL, and Cammidge AN
- Abstract
Phthalocyanines and porphyrins are often the scaffolds of choice for use in widespread applications. Synthetic advances allow bespoke derivatives to be made, tailoring their properties. The selective synthesis of unsymmetrical systems, particularly phthalocyanines, has remained a significant unmet challenge. Porphyrin-phthalocyanine hybrids offer the potential to combine the favorable features of both parent structures, but again synthetic strategies are poorly developed. Here we demonstrate strategies that give straightforward, controlled access to differentially substituted meso-aryl-tetrabenzotriazaporphyrins by reaction between an aryl-aminoisoindolene (A) initiator and a complementary phthalonitrile (B). The choice of precursors and reaction conditions allows selective preparation of 1:3 Ar-ABBB and, uniquely, 2:2 Ar-ABBA functionalized hybrids., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
- Published
- 2021
- Full Text
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23. Peptide directed phthalocyanine-gold nanoparticles for selective photodynamic therapy of EGFR overexpressing cancers.
- Author
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Goddard ZR, Beekman AM, Cominetti MMD, O'Connell MA, Chambrier I, Cook MJ, Marín MJ, Russell DA, and Searcey M
- Abstract
Gold nanoparticles, covalently functionalised with the photosensitiser C11Pc and PEG, were actively targeted towards epidermal growth factor receptor overexpressing cancers using the peptide FITC-βAAEYLRK. Selective phototoxicity was observed at nanomolar concentrations with minimal dark toxicity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
- Published
- 2020
- Full Text
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24. Do Gold(III) Complexes Form Hydrogen Bonds? An Exploration of Au III Dicarboranyl Chemistry.
- Author
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Chambrier I, Hughes DL, Jeans RJ, Welch AJ, Budzelaar PHM, and Bochmann M
- Abstract
The reaction of 1,1'-Li
2 [(2,2'-C2 B10 H10 )2 ] with the cyclometallated gold(III) complex (C^N)AuCl2 afforded the first examples of gold(III) dicarboranyl complexes. The reactivity of these complexes is subject to the trans-influence exerted by the dicarboranyl ligand, which is substantially weaker than that of non-carboranyl anionic C-ligands. In line with this, displacement of coordinated pyridine by chloride is only possible under forcing conditions. While treatment of (C^N)Au{(2,2'-C2 B10 H10 )2 } (2) with triflic acid leads to Au-C rather than Au-N bond protonolysis, aqueous HBr cleaves the Au-N bond to give the pyridinium bromo complex 7. The trans-influence of a series of ligands including dicarboranyl and bis(dicarboranyl) was assessed by means of DFT calculations. The analysis demonstrated that it was not sufficient to rely exclusively on geometric descriptors (calculated or experimental) when attempting to rank ligands for their trans influence. Complex (C^N)Au(C2 B10 H11 )2 containing two non-chelating dicarboranyl ligands was prepared similar to 2. Its reaction with trifluoroacetic acid also leads to Au-N cleavage to give trans-(Hpy^C)Au(OAcF )(C2 B10 H11 )2 (8). In crystals of 8 the pyridinium N-H bond points towards the metal centre, while in 7 it is bent away. The possible contribution of gold(III)⋅⋅⋅H-N hydrogen bonding in these complexes was investigated by DFT calculations. The results show that, unlike the situation for platinum(II), there is no evidence for an energetically significant contribution by hydrogen bonding in the case of gold(III)., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2020
- Full Text
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25. Evolutionary Computation for Parameter Extraction of Organic Thin-Film Transistors Using Newly Synthesized Liquid Crystalline Nickel Phthalocyanine.
- Author
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Jiménez-Tejada JA, Romero A, González J, Chaure NB, Cammidge AN, Chambrier I, Ray AK, and Deen MJ
- Abstract
In this work, the topic of the detrimental contact effects in organic thin-film transistors (OTFTs) is revisited. In this case, contact effects are considered as a tool to enhance the characterization procedures of OTFTs, achieving more accurate values for the fundamental parameters of the transistor threshold voltage, carrier mobility and on-off current ratio. The contact region is also seen as a fundamental part of the device which is sensitive to physical, chemical and fabrication variables. A compact model for OTFTs, which includes the effects of the contacts, and a recent proposal of an associated evolutionary parameter extraction procedure are reviewed. Both the model and the procedure are used to assess the effect of the annealing temperature on a nickel-1,4,8,11,15,18,22,25-octakis(hexyl)phthalocyanine (NiPc
6 )-based OTFT. A review of the importance of phthalocyanines in organic electronics is also provided. The characterization of the contact region in NiPc6 OTFTs complements the results extracted from other physical-chemical techniques such as differential scanning calorimetry or atomic force microscopy, in which the transition from crystal to columnar mesophase imposes a limit for the optimum performance of the annealed OTFTs.- Published
- 2019
- Full Text
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26. Thermally Stable Gold(III) Alkene and Alkyne Complexes: Synthesis, Structures, and Assessment of the trans-Influence on Gold-Ligand Bond Enthalpies.
- Author
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Chambrier I, Rocchigiani L, Hughes DL, Budzelaar PMH, and Bochmann M
- Abstract
The reaction of [C^C)Au(OEt
2 )2 ]+ with 1,5-cyclooctadiene or norbornadiene affords the corresponding olefin complexes [(C^C)Au(COD)]SbF6 and [(C^C)Au(NBD)]SbF6 , which are thermally stable in solution and the solid state (C^C=4,4'-di-tert-butylbiphenyl-2,2'-diyl). The crystal structures of these complexes have been determined. By contrast, dienones such as dibenzylideneacetone are O- rather than C=C-bonded. The reactions of (C^C)Au(OAcF )(L) (L=PMe3 or CNxyl) with B(C6 F5 )3 in the presence of bis(1-adamantyl)acetylene give the mixed-ligand alkyne complexes [(C^C)Au(AdC≡CAd)(L)]+ , the first complexes of their type in gold chemistry. In the presence of an excess of acetylene these compounds are thermally stable in solution and as solids. The bonding of n- and π-donor ligands to AuIII fragments and the effect of the trans influence exerted by N- and C-donors was explored with the aid of DFT calculations. Results show that the Au-L bond enthalpies trans to anionic C are 35-60 % of the enthalpies trans to N, with strong π-acceptors being particularly affected. In comparison with [Me2 Au]+ , the [(C^C)Au]+ fragment is more polar and in bond enthalpy terms resembles Me2 Pt., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2018
- Full Text
- View/download PDF
27. Unlocking Structural Diversity in Gold(III) Hydrides: Unexpected Interplay of cis/ trans-Influence on Stability, Insertion Chemistry, and NMR Chemical Shifts.
- Author
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Rocchigiani L, Fernandez-Cestau J, Chambrier I, Hrobárik P, and Bochmann M
- Abstract
The synthesis of new families of stable or at least spectroscopically observable gold(III) hydride complexes is reported, including anionic cis-hydrido chloride, hydrido aryl, and cis-dihydride complexes. Reactions between (C^C)AuCl(PR
3 ) and LiHBEt3 afford the first examples of gold(III) phosphino hydrides (C^C)AuH(PR3 ) (R = Me, Ph, p-tolyl; C^C = 4,4'-di- tert-butylbiphenyl-2,2'-diyl). The X-ray structure of (C^C)AuH(PMe3 ) was determined. LiHBEt3 reacts with (C^C)AuCl(py) to give [(C^C)Au(H)Cl]- , whereas (C^C)AuH(PR3 ) undergoes phosphine displacement, generating the dihydride [(C^C)AuH2 ]- . Monohydrido complexes hydroaurate dimethylacetylene dicarboxylate to give Z-vinyls. (C^N^C)Au pincer complexes give the first examples of gold(III) bridging hydrides. Stability, reactivity and bonding characteristics of Au(III)-H complexes crucially depend on the interplay between cis and trans-influence. Remarkably, these new gold(III) hydrides extend the range of observed NMR hydride shifts from δ -8.5 to +7 ppm. Relativistic DFT calculations show that the origin of this wide chemical shift variability as a function of the ligands depends on the different ordering and energy gap between "shielding" Au(dπ )-based orbitals and "deshielding" σ(Au-H)-type MOs, which are mixed to some extent upon inclusion of spin-orbit (SO) coupling. The resulting1 H hydride shifts correlate linearly with the DFT optimized Au-H distances and Au-H bond covalency. The effect of cis ligands follows a nearly inverse ordering to that of trans ligands. This study appears to be the first systematic delineation of cis ligand influence on M-H NMR shifts and provides the experimental evidence for the dramatic change of the1 H hydride shifts, including the sign change, upon mutual cis and trans ligand alternation.- Published
- 2018
- Full Text
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28. Towards optimisation of surface enhanced photodynamic therapy of breast cancer cells using gold nanoparticle-photosensitiser conjugates.
- Author
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García Calavia P, Marín MJ, Chambrier I, Cook MJ, and Russell DA
- Subjects
- Cell Line, Tumor, Female, Gold chemistry, Humans, Microscopy, Confocal, Models, Molecular, Organometallic Compounds chemistry, Organometallic Compounds pharmacology, Photosensitizing Agents chemical synthesis, Photosensitizing Agents chemistry, Singlet Oxygen chemistry, Breast Neoplasms therapy, Gold pharmacology, Metal Nanoparticles, Organometallic Compounds chemical synthesis, Photochemotherapy trends, Photosensitizing Agents pharmacology, Polyethylene Glycols chemistry
- Abstract
Gold nanoparticles (AuNPs; ca. 4 nm) were synthesised and functionalised with a mixed monolayer of polyethylene glycol (PEG) and one of two zinc phthalocyanines (ZnPcs), the difference between the two molecules was the length of the carbon chain that connects the Pc to the gold core. The chain was composed of either three (C3Pc) or eleven (C11Pc) carbon atoms. The C11Pc photosensitiser displayed higher fluorescence emission intensity than the C3Pc in solution. By contrast, the C3Pc photosensitiser exhibited higher fluorescence when bound to the surface of the AuNPs than the C11Pc, despite the shorter carbon chain which was expected to quench the fluorescence. In addition, the C3Pc nanoparticle conjugates exhibited an enhancement in the production of singlet oxygen (
1 O2 ). The metal-enhanced1 O2 production led to a remarkable photodynamic efficacy for the treatment of human breast cancer cells.- Published
- 2018
- Full Text
- View/download PDF
29. Targeted photodynamic therapy of breast cancer cells using lactose-phthalocyanine functionalized gold nanoparticles.
- Author
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García Calavia P, Chambrier I, Cook MJ, Haines AH, Field RA, and Russell DA
- Subjects
- Breast Neoplasms drug therapy, Breast Neoplasms metabolism, Female, Galectin 1 metabolism, Humans, Isoindoles, Metal Nanoparticles chemistry, Photosensitizing Agents chemistry, Tumor Cells, Cultured, Breast Neoplasms pathology, Gold chemistry, Indoles chemistry, Lactose chemistry, Metal Nanoparticles administration & dosage, Photochemotherapy, Photosensitizing Agents pharmacology
- Abstract
Gold nanoparticles (AuNPs), which have been widely used for the delivery of photosensitizers for photodynamic therapy (PDT) of cancer, can be dispersed in aqueous solutions improving the delivery of the hydrophobic photosensitizer into the body. Furthermore, the large surface of AuNPs can be functionalized with a variety of ligands, including proteins, nucleic acids and carbohydrates, that allow selective targeting to cancer tissue. In this study, gold nanoparticles were functionalized with a mixed monolayer of a zinc phthalocyanine and a lactose derivative. For the first time, a carbohydrate was used with a dual purpose, as the stabilizing agent of the gold nanoparticles in aqueous solutions and as the targeting agent for breast cancer cells. The functionalization of the phthalocyanine-AuNPs with lactose led to the production of water-dispersible nanoparticles that are able to generate singlet oxygen and effect cell death upon irradiation. The targeting ability of lactose of the lactose-phthalocyanine functionalized AuNPs was studied in vitro towards the galectin-1 receptor on the surface of breast cancer cells. The targeting studies showed the exciting potential of lactose as a specific targeting agent for galactose-binding receptors overexpressed on breast cancer cells., (Copyright © 2017 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
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30. Gold(III) Alkyne Complexes: Bonding and Reaction Pathways.
- Author
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Rocchigiani L, Fernandez-Cestau J, Agonigi G, Chambrier I, Budzelaar PHM, and Bochmann M
- Abstract
The synthesis and characterization of hitherto hypothetical Au
III π-alkyne complexes is reported. Bonding and stability depend strongly on the trans effect and steric factors. Bonding characteristics shed light on the reasons for the very different stabilities between the classical alkyne complexes of PtII and their drastically more reactive AuIII congeners. Lack of back-bonding facilitates alkyne slippage, which is energetically less costly for gold than for platinum and explains the propensity of gold to facilitate C-C bond formation. Cycloaddition followed by aryl migration and reductive deprotonation is presented as a new reaction sequence in gold chemistry., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2017
- Full Text
- View/download PDF
31. Formation of Gold(III) Alkyls from Gold Alkoxide Complexes.
- Author
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Chambrier I, Roşca DA, Fernandez-Cestau J, Hughes DL, Budzelaar PHM, and Bochmann M
- Abstract
The gold(III) methoxide complex (C
∧ N∧ C)AuOMe ( 1 ) reacts with tris( p -tolyl)phosphine in benzene at room temperature under O abstraction to give the methylgold product (C∧ N∧ C)AuMe ( 2 ) together with O=P( p -tol)3 ((C∧ N∧ C) = [2,6-(C6 H3 t Bu-4)2 pyridine]2- ). Calculations show that this reaction is energetically favorable (Δ G = -32.3 kcal mol-1 ). The side products in this reaction, the Au(II) complex [Au(C∧ N∧ C)]2 ( 3 ) and the phosphorane ( p -tol)3 P(OMe)2 , suggest that at least two reaction pathways may operate, including one involving (C∧ N∧ C)Au• radicals. Attempts to model the reaction by DFT methods showed that PPh3 can approach 1 to give a near-linear Au-O-P arrangement, without phosphine coordination to gold. The analogous reaction of (C∧ N∧ C)AuOEt, on the other hand, gives exclusively a mixture of 3 and ( p -tol)3 P(OEt)2 . Whereas the reaction of (C∧ N∧ C)AuOR (R = But , p -C6 H4 F) with P( p -tol)3 proceeds over a period of hours, compounds with R = CH2 CF3 , CH(CF3 )2 react almost instantaneously, to give 3 and O=P( p -tol)3 . In chlorinated solvents, treatment of the alkoxides (C∧ N∧ C)AuOR with phosphines generates [(C∧ N∧ C)Au(PR3 )]Cl, via Cl abstraction from the solvent. Attempts to extend the synthesis of gold(III) alkoxides to allyl alcohols were unsuccessful; the reaction of (C∧ N∧ C)AuOH with an excess of CH2 =CHCH2 OH in toluene led instead to allyl alcohol isomerization to give a mixture of gold alkyls, (C∧ N∧ C)AuR' (R' = -CH2 CH2 CHO ( 10 ), -CH2 CH(CH2 OH)OCH2 CH=CH2 ( 11 )), while 2-methallyl alcohol affords R' = CH2 CH(Me)CHO ( 12 ). The crystal structure of 11 was determined. The formation of Au-C instead of the expected Au-O products is in line with the trend in metal-ligand bond dissociation energies for Au(III): M-H > M-C > M-O.- Published
- 2017
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32. Delivery of a hydrophobic phthalocyanine photosensitizer using PEGylated gold nanoparticle conjugates for the in vivo photodynamic therapy of amelanotic melanoma.
- Author
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Camerin M, Moreno M, Marín MJ, Schofield CL, Chambrier I, Cook MJ, Coppellotti O, Jori G, and Russell DA
- Subjects
- Animals, Female, Gold chemistry, Hydrophobic and Hydrophilic Interactions, Indoles chemistry, Indoles pharmacokinetics, Indoles therapeutic use, Isoindoles, Melanoma, Amelanotic metabolism, Melanoma, Amelanotic pathology, Metal Nanoparticles chemistry, Mice, Inbred C57BL, Organometallic Compounds chemistry, Organometallic Compounds pharmacokinetics, Organometallic Compounds therapeutic use, Photochemotherapy, Photosensitizing Agents chemistry, Photosensitizing Agents pharmacokinetics, Photosensitizing Agents therapeutic use, Polyethylene Glycols chemistry, Skin metabolism, Skin pathology, Skin Neoplasms metabolism, Skin Neoplasms pathology, Zinc Compounds, Drug Carriers chemistry, Indoles administration & dosage, Melanoma, Amelanotic drug therapy, Organometallic Compounds administration & dosage, Photosensitizing Agents administration & dosage, Skin drug effects, Skin Neoplasms drug therapy
- Abstract
Photodynamic therapy (PDT) is a treatment of cancer whereby tumours are destroyed by reactive oxygen species generated upon photoactivation of a photosensitizer drug. Hydrophobic photosensitizers are known to be ideal for PDT; however, their hydrophobicity necessitates that they are typically administered using emulsions. Here, a delivery vehicle for photodynamic therapy based on the co-self-assembly of both a Zn(ii)-phthalocyanine derivative photosensitizer and a polyethylene glycol (PEG) derivative onto gold nanoparticles is reported. The PEG on the particle surface ensured that the conjugates were water soluble and enhanced their retention in the serum, improving the efficiency of PDT in vivo. The pharmacokinetic behaviour of the nanoparticle conjugates following intravenous injection into C57/BL6 mice bearing a subcutaneous transplanted B78H1 amelanotic melanoma showed a significant increase of retention of the nanoparticles in the tumour. PDT tumour destruction was achieved 3 h following injection of the nanoparticle conjugates leading to a remarkable 40% of the treated mice showing no tumour regrowth and complete survival. These results highlight that dual functionalised nanoparticles exhibit significant potential in PDT of cancer especially for difficult to treat cancers such as amelanotic melanoma.
- Published
- 2016
- Full Text
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33. Synthesis of Porphyrin-CdSe Quantum Dot Assemblies: Controlling Ligand Binding by Substituent Effects.
- Author
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Chambrier I, Banerjee C, Remiro-Buenamañana S, Chao Y, Cammidge AN, and Bochmann M
- Abstract
Cadmium selenide quantum dots of 2.2-2.3 nm diameter were prepared by phosphorus-free methods using oleic acid as stabilizing surface ligand. Ligand exchange monitored quantitatively by (1)H NMR spectroscopy gave an estimate of 30-38 monodentate ligands per nanocrystal, with a ligand density of 1.8-2.3 nm(-2). The extent of ligand exchange with macrocycles carrying one or more functional groups was investigated, with the aim of producing nanocrystal-macrocycle conjugates with a limited number of coligands. Metal-free porphyrins are able to sequester the Cd(2+) ions from the Cd(oleate)2 outer layer of the nanocrystals. Zinc porphyrin complexes carrying one carboxylate function displace oleate efficiently to give porphyrin/CdSe composites with porphyrins stacked upright on the crystal surface. Porphyrins with four potential ligating sites are able to bind to the crystal surface only if the donors are at the end of sufficiently long and flexible tethers. High-dilution methods allowed the synthesis and isolation of well-defined composites of composition [CdSe{porphyrin}2], where porphyrin = 5,10,15,20-tetrakis{3-(carboxy-n-alkyloxy)phenyl}porphyrinato zinc (n = 5 or 10) and 5,10,15,20-tetrakis{3-(11-undecenyloxythiol)phenyl}porphyrinato zinc. Comparison of the composition data obtained by (1)H NMR spectroscopy with luminescence quenching behavior suggests a dependence of quenching efficiency on the tether length. Luminescence quenching was also observed for porphyrins that, according to (1)H NMR results, do not undergo surface ligand exchange.
- Published
- 2015
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34. Tetrabenzoporphyrin and -mono-, -cis-di- and Tetrabenzotriazaporphyrin Derivatives: Electrochemical and Spectroscopic Implications of meso CH Group Replacement with Nitrogen.
- Author
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van As A, Joubert CC, Buitendach BE, Erasmus E, Conradie J, Cammidge AN, Chambrier I, Cook MJ, and Swarts JC
- Subjects
- Crystallography, X-Ray, Electrochemical Techniques, Isoindoles, Magnetic Resonance Spectroscopy, Models, Molecular, Photoelectron Spectroscopy, Spectrophotometry, Ultraviolet, Benzene Derivatives chemistry, Coordination Complexes chemistry, Copper chemistry, Indoles chemistry, Nitrogen chemistry, Porphyrins chemistry
- Abstract
Nonperipherally hexyl-substituted metal-free tetrabenzoporphyrin (2H-TBP, 1a) tetrabenzomonoazaporphyrin (2H-TBMAP, 2a), tetrabenzo-cis-diazaporphyrin (2H-TBDAP, 3a), tetrabenzotriazaporphyrin (2H-TBTAP, 4a), and phthalocyanine (2H-Pc, 5a), as well as their copper complexes (1b-5b), were synthesized. As the number of meso nitrogen atoms increases from zero to four, λmax of the Q-band absorption peak becomes red-shifted by almost 100 nm, and extinction coefficients increased at least threefold. Simultaneously the blue-shifted Soret (UV) band substantially decreased in intensity. These changes were related to the relative electron-density of each macrocycle expressed as the group electronegativity sum of all meso N and CH atom groups, ∑χR. X-ray photoelectron spectroscopy differentiated between the three different types of macrocyclic nitrogen atoms (the Ninner, (NH)inner, and Nmeso) in the metal-free complexes. Binding energies of the Nmeso and Ninner,Cu atoms in copper chelates could not be resolved. Copper insertion lowered especially the cathodic redox potentials, while all four observed redox processes occurred at larger potentials as the number of meso nitrogens increased. Computational chemical methods using density functional theory confirmed 1b to exhibit a Cu(II) reduction prior to ring-based reductions, while for 2b, Cu(II) reduction is the first reductive step only if the nonperipheral substituents are hydrogen. When they are methyl groups, it is the second reduction process; when they are ethyl, propyl, or hexyl, it becomes the third reductive process. Spectro-electrochemical measurements showed redox processes were associated with a substantial change in intensity of at least two main absorbances (the Q and Soret bands) in the UV spectra of these compounds.
- Published
- 2015
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- View/download PDF
35. Cancer targeting with biomolecules: a comparative study of photodynamic therapy efficacy using antibody or lectin conjugated phthalocyanine-PEG gold nanoparticles.
- Author
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Obaid G, Chambrier I, Cook MJ, and Russell DA
- Subjects
- Adenocarcinoma drug therapy, Adenocarcinoma metabolism, Adenocarcinoma pathology, Antibodies, Monoclonal chemistry, Antigens, Tumor-Associated, Carbohydrate chemistry, Antineoplastic Agents chemistry, Breast Neoplasms drug therapy, Breast Neoplasms metabolism, Breast Neoplasms pathology, Cell Line, Tumor, Cell Survival drug effects, Colorectal Neoplasms drug therapy, Colorectal Neoplasms metabolism, Colorectal Neoplasms pathology, Gold Compounds chemistry, Gold Compounds therapeutic use, Humans, Hydrophobic and Hydrophilic Interactions, Indoles chemistry, Isoindoles, Lectins chemistry, Lectins therapeutic use, Lysosomes drug effects, Lysosomes metabolism, Lysosomes pathology, Metal Nanoparticles chemistry, Organometallic Compounds chemistry, Photosensitizing Agents chemistry, Polyethylene Glycols chemistry, Polyethylene Glycols therapeutic use, Receptor, ErbB-2 immunology, Singlet Oxygen chemistry, Zinc Compounds, Antineoplastic Agents administration & dosage, Indoles administration & dosage, Indoles therapeutic use, Metal Nanoparticles therapeutic use, Molecular Targeted Therapy methods, Organometallic Compounds therapeutic use, Photochemotherapy methods, Photosensitizing Agents administration & dosage
- Abstract
The functionalisation of therapeutic nanoparticle constructs with cancer-specific biomolecules can enable selective tumour accumulation and targeted treatment. Water soluble gold nanoparticles (ca. 4 nm) stabilised by a mixed monolayer of a hydrophobic zinc phthalocyanine photosensitiser (C11Pc) and hydrophilic polyethylene glycol (PEG) have been prepared. The C11Pc-PEG gold nanoparticle constructs were further functionalised with jacalin, a lectin specific for the cancer-associated Thomsen-Friedenreich (T) carbohydrate antigen, or with monoclonal antibodies specific for the human epidermal growth factor receptor-2 (HER-2). The two biofunctionalised nanoparticle conjugates produced similar levels of singlet oxygen upon irradiation at 633 nm. Importantly, both nanoparticle conjugates demonstrated extensive, yet comparable, phototoxicity in HT-29 colorectal adenocarcinoma cells (80-90%) and in SK-BR-3 breast adenocarcinoma cells (>99%). Non-conjugated C11Pc-PEG gold nanoparticles were only minimally phototoxic. Lysosomal colocalisation studies performed with the HT-29 colon cancer cells and the SK-BR-3 breast cancer cells revealed that both nanoparticle conjugates were partially localised within acidic organelles, which is typical of receptor-mediated endocytosis. The similarity of the targeted PDT efficacy of the two biofunctionalised C11Pc-PEG gold nanoparticles is discussed with respect to targeting ligand binding affinity and cell surface antigen density as key determinants of targeting efficiency. This study highlights how targeting small cell-surface molecules, such as the T antigen, can mediate a selective photodynamic treatment response which is similar to that achieved when targeting overexpressed protein receptors, such as HER-2. The high prevalence of the T antigen present on the cellular surface of primary tumours emphasises the broad potential applications for lectin-targeted therapies.
- Published
- 2015
- Full Text
- View/download PDF
36. Expanded porphyrin-like structures based on twinned triphenylenes.
- Author
-
Gopee H, Kong X, He Z, Chambrier I, Hughes DL, Tizzard GJ, Coles SJ, and Cammidge AN
- Subjects
- Models, Molecular, Molecular Structure, Chrysenes chemistry
- Abstract
Triphenylene twins are intriguing structures, and those bridged through their 3,6-positions by dipyrromethene units give a new class of macrocycles that can be viewed as rigid, expanded porphyrin derivatives in which coplanarity is enforced in a formally antiaromatic π system. Somewhat surprisingly, however, macrocyclization leads to significant overall stabilization of the dipyrromethene chromophores.
- Published
- 2013
- Full Text
- View/download PDF
37. Synthesis of D-mannose capped silicon nanoparticles and their interactions with MCF-7 human breast cancerous cells.
- Author
-
Ahire JH, Chambrier I, Mueller A, Bao Y, and Chao Y
- Subjects
- Cell Line, Tumor, Cytoplasm metabolism, Female, Humans, Light, MCF-7 Cells, Magnetic Resonance Spectroscopy methods, Materials Testing, Microscopy, Electron, Transmission methods, Scattering, Radiation, Spectrometry, X-Ray Emission, Spectroscopy, Fourier Transform Infrared methods, Surface Properties, Breast Neoplasms metabolism, Concanavalin A chemistry, Mannose chemistry, Nanoparticles chemistry, Nanotechnology methods, Silicon chemistry
- Abstract
Silicon nanoparticles (SiNPs) hold prominent interest in various aspects of biomedical applications. For this purpose, surface functionalization of the NPs is essential to stabilize them, target them to specific disease area, and allow them to selectively bind to the cells or the bio-molecules present on the surface of the cells. However, no such functionalization has been explored with Si nanoparticles. Carbohydrates play a critical role in cell recognition. Here, we report the first synthesis of silicon nanoparticles functionalized with carbohydrates. In this study, stable and brightly luminescent d-Mannose (Man) capped SiNPs have been synthesized from amine terminated SiNPs and d-mannopyranoside acid. The surface functionalization is confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and energy dispersive X-ray spectroscopy (EDX) studies. The mean diameter of the crystal core is 5.5 nm, as measured by transmission electron microscopy (TEM), while the hydrodynamic diameter obtained by dynamic light scattering (DLS) is 16 nm. The quantum yield (QY) of photoluminescence emission is found to be 11.5%, and the nanoparticles exhibit an exceptional stability over two weeks. The Man-capped SiNPs may prove to be valuable tools for further investigating glycobiological, biomedical, and material science fields. Experiments are carried out using Concanavalin A (ConA) as a target protein in order to prove the hypothesis. When Man functionalized SiNPs are treated with ConA, cross-linked aggregates are formed, as shown in TEM images as well as monitored by photoluminescence spectroscopy (PL). Man functionalized SiNPs can target cancerous cells. Visualization imaging of SiNPs in MCF-7 human breast cancer cells shows the fluorescence is distributed throughout the cytoplasm of these cells.
- Published
- 2013
- Full Text
- View/download PDF
38. Synthesis, characterization, MCD spectroscopy, and TD-DFT calculations of copper-metalated nonperipherally substituted octaoctyl derivatives of tetrabenzotriazaporphyrin, cis- and trans-tetrabenzodiazaporphyrin, tetrabenzomonoazaporphyrin, and tetrabenzoporphyrin.
- Author
-
Mack J, Sosa-Vargas L, Coles SJ, Tizzard GJ, Chambrier I, Cammidge AN, Cook MJ, and Kobayashi N
- Subjects
- Circular Dichroism, Models, Molecular, Molecular Structure, Organometallic Compounds chemistry, Stereoisomerism, Copper chemistry, Organometallic Compounds chemical synthesis, Porphyrins chemical synthesis, Porphyrins chemistry, Quantum Theory
- Abstract
Synthesis of the title compounds has been achieved through refinement of a recently reported synthetic protocol whereby varying equivalents of MeMgBr are reacted with 1,4-dioctylphthalonitrile to produce mixtures favoring specific hybrid structures. The initially formed magnesium-metalated compounds are obtained as pure materials and include, for the first time, both isomers (cis and trans) of tetrabenzodiazaporphyrin. The compounds were demetalated to the metal-free analogues, which were then converted into the copper-metalated derivatives. The X-ray structure of the copper tetrabenzotriazaporphyrin derivative is reported. The metal-free and copper-metalated macrocycles exhibit columnar mesophase behavior, and it is found that the mesophase stability is unexpectedly reduced in the diazaporphyrin derivatives compared to the rest of the series. The results of time-dependent density functional theory calculations for the copper complexes are compared to the observed optical properties. Michl's perimeter model was used as a conceptual framework for analyzing the magnetic circular dichroism spectral data, which predicted and accounted for trends in the observed experimental spectra.
- Published
- 2012
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- View/download PDF
39. Targeting the oncofetal Thomsen-Friedenreich disaccharide using jacalin-PEG phthalocyanine gold nanoparticles for photodynamic cancer therapy.
- Author
-
Obaid G, Chambrier I, Cook MJ, and Russell DA
- Subjects
- Cell Line, Tumor, Drug Delivery Systems, Humans, Isoindoles, Microscopy, Confocal, Photosensitizing Agents chemistry, Antigens, Viral, Tumor drug effects, Gold chemistry, Indoles chemistry, Metal Nanoparticles chemistry, Neoplasms drug therapy, Photochemotherapy, Plant Lectins chemistry, Polyethylene Glycols chemistry
- Published
- 2012
- Full Text
- View/download PDF
40. High-mobility solution-processed copper phthalocyanine-based organic field-effect transistors.
- Author
-
Chaure NB, Cammidge AN, Chambrier I, Cook MJ, Cain MG, Murphy CE, Pal C, and Ray AK
- Abstract
Solution-processed films of 1,4,8,11,15,18,22,25-octakis(hexyl) copper phthalocyanine (CuPc
6 ) were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs) in the bottom-gate configurations using chemical vapour deposited silicon dioxide (SiO2 ) as gate dielectrics. The surface treatment of the gate dielectric with a self-assembled monolayer of octadecyltrichlorosilane (OTS) resulted in values of 4×10-2 cm2 V-1 s-1 and 106 for saturation mobility and on/off current ratio, respectively. This improvement was accompanied by a shift in the threshold voltage from 3 V for untreated devices to -2 V for OTS treated devices. The trap density at the interface between the gate dielectric and semiconductor decreased by about one order of magnitude after the surface treatment. The transistors with the OTS treated gate dielectrics were more stable over a 30-day period in air than untreated ones.- Published
- 2011
- Full Text
- View/download PDF
41. Phthalocyanine analogues: unexpectedly facile access to non-peripherally substituted octaalkyl tetrabenzotriazaporphyrins, tetrabenzodiazaporphyrins, tetrabenzomonoazaporphyrins and tetrabenzoporphyrins.
- Author
-
Cammidge AN, Chambrier I, Cook MJ, Hughes DL, Rahman M, and Sosa-Vargas L
- Abstract
Controlled syntheses of phthalocyanine/benzoporphyrin hybrid structures have been achieved. We report a simple means for obtaining non-peripherally octaalkyl-substituted derivatives of tetrabenzotriazaporphyrin (TBTAP), tetrabenzodiazaporphyrin (TBDAP), tetrabenzomonoazaporphyrin (TBMAP) and tetrabenzoporphyrin (TBP) macrocycles by treating 3,6-dialkyl phthalonitriles with differing amounts of the Grignard reagent MeMgBr. This range of macrocyclic products is not obtained from corresponding reactions of a Grignard reagent with 4-substituted phthalonitriles, reported previously, or reaction of MeMgBr with a 4,5-dialkyl phthalonitrile. Attempts to form a meso-substituted TBTAP from 3,6-dialkyl phthalonitriles by reaction with benzyl and long-chain alkyl Grignard reagents unexpectedly gave only the parent macrocycle unsubstituted at the meso position. The synthetic protocols are by far the most straightforward and convenient means to access these interesting, but scarcely studied, classes of material. The new series of substituted macrocyclic compounds, obtained as the metal-free and magnesium- and copper(II)-metallated derivatives, show trends in the UV/Vis spectra consistent with those predicted elsewhere by Kobayashi. Characterisation of the new families allows further trends to be identified as meso-nitrogen atoms are sequentially replaced by methine bridges, for example, the compounds provide novel examples of macrocyclic structures that show columnar mesophase behaviour. Single-crystal X-ray structure determinations have been obtained for three magnesium-metallated derivatives bearing eight hexyl substituents and constitute the first set of structural data obtained for such a series., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2011
- Full Text
- View/download PDF
42. Electrochemical and spectroscopic detection of self-association of octa-alkyl phthalocyaninato cadmium compounds into dimeric species.
- Author
-
Fourie E, Swarts JC, Chambrier I, and Cook MJ
- Subjects
- Dimerization, Electrochemistry, Isoindoles, Molecular Structure, Oxidation-Reduction, Spectrophotometry, Ultraviolet, Cadmium chemistry, Indoles chemistry, Magnetic Resonance Spectroscopy, Organometallic Compounds chemistry
- Abstract
The solution phase behaviour of non-peripherally substituted octa-hexyl cadmium phthalocyanine 3 and peripherally substituted octa-2-ethylhexyl cadmium phthalocyanine has been investigated in fresh solutions of CH(2)Cl(2), CHCl(3)-d(1) and THF/THF-d(8) using (1)H NMR spectrometry, UV-Vis spectroscopy, cyclic voltammetry, square wave voltammetry and linear sweep voltammetry. The compounds show an unexpected propensity to form dimeric species in CH(2)Cl(2) and CHCl(3)-d(1), and, in the case of , also to a lesser extent in THF/THF-d(8). This phenomenon is not observed for their metal-free analogues or . The electrochemical results provide particularly strong evidence for the dimeric structures. In particular both the first one-electron oxidation and one-electron reduction waves for 3 and 4, unlike those of and , are split. This is consistent with sequential oxidation/reduction of the two Pc ligands within a dimer. The dimeric species are likely to be the immediate precursors of the recently discovered bis-cadmium tris-phthalocyanine triple-decker sandwich complexes and formed from and over a period of time. The electrochemical data for compounds also show that (i) relative to the metal-free phthalocyanines, the cadmium phthalocyanines exhibit smaller formal reduction potentials for all but one of the observed electron transfer processes and (ii) the electron transfer processes associated with the peripherally substituted compounds, 2 and 4, are observed at more positive potentials than those for the corresponding non-peripherally substituted analogues 1 and 3.
- Published
- 2009
- Full Text
- View/download PDF
43. Electrochemical and EPR studies of two substituted bis-cadmium tris-phthalocyanine complexes: elucidation of unexpectedly different free-radical character.
- Author
-
Cook MJ, Chambrier I, White GF, Fourie E, and Swarts JC
- Subjects
- Electrochemistry, Isoindoles, Molecular Structure, Oxidation-Reduction, Cadmium chemistry, Electron Spin Resonance Spectroscopy, Free Radicals chemistry, Indoles chemistry, Organometallic Compounds chemistry
- Abstract
The electronic and electron transfer behaviour of two examples of a recently discovered class of triple-decker sandwich complex based on three phthalocyanine ligands linked by two chelated cadmium ions has been investigated by EPR spectroscopy and cyclic voltammetry, square wave voltammetry and linear sweep voltammetry experiments. The two compounds, and , differ in the location of the eight alkyl groups attached to each of the phthalocyanine rings; at the non-peripheral sites in and the peripheral sites in . Quantitative comparison of the free radical character of and in solutions was undertaken by EPR spectroscopy and revealed that exists as a mixture of s = 0 and s = (1/2) species, whereas compound exists essentially as a spin (1/2) species alone. The electrochemical study of and was undertaken in both dichloromethane (CH(2)Cl(2)) and tetrahydrofuran (THF). The two compounds show comparable but subtly different redox behaviour which can only be attributed to the different locations of the substituents. Seventeen of the possible eighteen one-electron transfer processes could be identified for . The first oxidation wave for , both in THF and in CH(2)Cl(2) solutions, was encountered at ca. 160 mV lower potential than for implying that is much easier to initially oxidise than . This finding provides a rationale for the EPR results described above. In separate experiments, oxidation of and as solutions and spin-coated film formulations was achieved using iodine and was characterised by significant changes in the visible region absorption spectra of the compounds.
- Published
- 2009
- Full Text
- View/download PDF
44. Oligomeric cadmium-phthalocyanine complexes: novel supramolecular free radical structures.
- Author
-
Chambrier I, White GF, and Cook MJ
- Subjects
- Isoindoles, Molecular Structure, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Spectrophotometry, Ultraviolet, X-Ray Diffraction, Cadmium chemistry, Indoles chemistry
- Abstract
Certain cadmium-metallated phthalocyanines give rise to EPR active triple-decker sandwich complexes containing two Cd ions and three phthalocyanine (Pc) ligands. These have been shown to form when the ligands bear either eight non- peripheral alkyl or alkenyl substituents or eight peripheral 2-ethylhexyl groups. They can be derived either from three equivalents of a cadmium phthalocyanine precursor or from a 2:1 mixture of a cadmium phthalocyanine (CdPc) and a metal-free phthalocyanine (H(2)Pc). The mode of their formation has been investigated by a series of "cross" experiments. The results indicate that the triple-decker structures are formed by a self-assembly process. This is deduced from results that show that they can disassemble and reassemble with incorporation of differently substituted ligands derived from either an H(2)Pc or CdPc. The reassembled structures in these cross experiments can contain more than one ligand that originated from either the added CdPc or, and more surprisingly, the H(2)Pc compound. Mass spectrometry has also established that higher order oligomers can be formed when steric requirements between the alkyl substituents on adjacent rings in the stack are reduced. Thus an isotopic cluster for a Cd(5)Pc(6) complex has been observed when the eight peripheral substituents are hexyl chains and tetrameric complexes are formed when two different ligands are incorporated within a stack, with one carrying substituents at the peripheral sites and the other bearing substituents at the non-peripheral sites.
- Published
- 2007
- Full Text
- View/download PDF
45. First example of a di-cadmium tris-phthalocyanine triple-decker sandwich complex.
- Author
-
Chambrier I, Hughes DL, Swarts JC, Isare B, and Cook MJ
- Abstract
An unprecedented M(II)2Pc3 (M = Cd) triple-decker sandwich complex has been synthesized and characterised by single crystal X-ray crystallography; cyclic voltammetry shows an unusually large range of redox states and EPR spectroscopy indicates that the material exists in at least two redox states, one having spin (1/2).
- Published
- 2006
- Full Text
- View/download PDF
46. Zinc octa-n-alkyl phthalocyanines in photodynamic therapy: photophysical properties, accumulation and apoptosis in cell cultures, studies in erythrocytes and topical application to Balb/c mice skin.
- Author
-
Kaestner L, Cesson M, Kassab K, Christensen T, Edminson PD, Cook MJ, Chambrier I, and Jori G
- Subjects
- 3T3 Cells, Administration, Topical, Animals, Caspase 3, Caspases metabolism, Cell Survival drug effects, Erythrocytes metabolism, Female, Fibroblasts cytology, Fibroblasts metabolism, Hemolysis drug effects, Humans, Indoles chemistry, Isoindoles, Keratinocytes cytology, Keratinocytes metabolism, Mice, Mice, Inbred BALB C, Organometallic Compounds chemistry, Photosensitizing Agents chemistry, Singlet Oxygen chemistry, Skin cytology, Skin metabolism, Spectrophotometry methods, Zinc Compounds, Apoptosis drug effects, Erythrocytes drug effects, Indoles pharmacokinetics, Indoles pharmacology, Organometallic Compounds pharmacokinetics, Organometallic Compounds pharmacology, Photochemotherapy methods, Photosensitizing Agents pharmacokinetics, Photosensitizing Agents pharmacology, Skin drug effects
- Abstract
Two octa-substituted phthalocyanines, namely 1,4,8,11,15,18,22,25-octakis(decyl)phthalocyaninato zinc(II) (ZnODPc) and 1,4,8,11,15,18,22,25-octakis(pentyl)phthalocyaninato zinc(II) (ZnOPPc), were investigated for their use in photodynamic therapy (PDT) after topical application. Both substances exhibited favourable properties as photosensitisers in vitro: absorption maxima around 700 nm with absorption coefficients of about 190000 (M(-1) cm(-1)), a singlet oxygen quantum yield of 0.47 +/- 0.02 (ZnODPc), and good accumulation in keratinocytes and fibroblasts. Cell death after phthalocyanine-photosensitisation appeared to occur mainly via apoptosis. The in vivo experiments demonstrated a good accumulation of the phthalocyanines after topical application in a tetrahydrofuran-azone formulation onto the dorsal skin of Balb/c mice: [(4.6-4.7) +/- 1.0]% of deposited dye could be recovered after 3 h from deposition. ZnODPc showed significantly better skin-photosensitising properties than ZnOPPc and is therefore a potential candidate for the treatment of psoriasis.
- Published
- 2003
- Full Text
- View/download PDF
47. Octa-alkyl zinc phthalocyanines: potential photosensitizers for use in the photodynamic therapy of cancer.
- Author
-
Cook MJ, Chambrier I, Cracknell SJ, Mayes DA, and Russell DA
- Subjects
- Indoles chemistry, Isoindoles, Neoplasms drug therapy, Organometallic Compounds chemistry, Photosensitizing Agents chemistry, Structure-Activity Relationship, Zinc chemistry, Zinc pharmacology, Zinc Compounds, Indoles chemical synthesis, Indoles pharmacology, Organometallic Compounds chemical synthesis, Organometallic Compounds pharmacology, Photochemotherapy, Photosensitizing Agents chemical synthesis, Photosensitizing Agents pharmacology
- Abstract
The synthesis, characterization and electronic spectra of a series of nine 1,4,8,11,15,18,22,25-octa-alkyl zinc phthalocyanines (ZnPc), potential photosensitizers for the photodynamic therapy of cancer, are described. The substituents on the phthalocyanine (Pc) macrocycle "red-shift" the absorbance maximum, in cyclohexane, of all nine members of this series to a value of 703 +/- 2 nm, with a corrected fluorescence emission maximum for the octadecyl derivative of 715 nm. The solubilities and degree of aggregation of six examples in cyclohexane have been measured. The highest homologue, the octadecyl derivative, remains essentially unaggregated to a concentration of 1.5 x 10(-4) mol dm-3. the photostability of this Pc has been examined and the compound shown to be sensitive to photooxidation processes which lead to its decomposition to 3,6-bis-decylphthalimide. Known singlet oxygen quenchers inhibit the photodecomposition. In a comparative study, the octadecyl ZnPc underwent a more rapid photodecomposition than the corresponding metal-free derivative.
- Published
- 1995
- Full Text
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