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Reproducible materials that have detection properties towards a certain molecule are very important for applications in the fabrication of devices. Among all the substrates that are used, highly oriented pyrolytic graphite allows to clearly image a monolayer. On the other hand, cryptand molecules are versatile because they can sense certain analytes with high selectivity. The highly oriented pyrolytic graphite electrode was first functionalized with an aryl bearing a bromine or an alkyne group to further attach cryptand molecules to its surface. The functionalization was performed through the electroreduction of aryl diazonium salts. While functionalization with an aryl-bromine produced a 20 nm-thick dendritic layer, functionalization of the surface with an aryl bearing a terminal alkyne produced a 9.7 nm-thick multilayer. However, if the diazonium salt is prepared in situ, a 0.9 nm monolayer with aryl–alkyne groups is formed. The alkyne functionalized electrode reacted with a bromo-cryptand through a Sonogashira C–C coupling reaction yielding electrodes functionalized with cryptands. These were immersed in a solution of a Co(II) salt resulting in Co(II)-cryptate modified electrodes, highlighting the ability of the cryptands’ modified electrode to sense metal ions. The electrode surface was analyzed by X-ray photoelectron spectroscopy after each modification step, which confirmed the successful functionalization of the substrate with both the cryptand and the cryptate. Cyclic voltammetry studies showed stable current response after approximately six cycles. Different reduction processes were detected for both cryptand (−1.40 V vs. SCE) and cryptate (−1.22 V vs. SCE) modified highly oriented pyrolytic graphite.
Marcos Bento; Sara Realista; Ana Viana; Ana Ferraria; Paulo Martinho. Cryptand-Functionalized Highly Oriented Pyrolytic Graphite Electrodes. Sustainability 2021, 13, 4158 .
AMA StyleMarcos Bento, Sara Realista, Ana Viana, Ana Ferraria, Paulo Martinho. Cryptand-Functionalized Highly Oriented Pyrolytic Graphite Electrodes. Sustainability. 2021; 13 (8):4158.
Chicago/Turabian StyleMarcos Bento; Sara Realista; Ana Viana; Ana Ferraria; Paulo Martinho. 2021. "Cryptand-Functionalized Highly Oriented Pyrolytic Graphite Electrodes." Sustainability 13, no. 8: 4158.
A facile access to a series of Mn(0) and Mn(i) complexes bearing triazolylidenes with either bridging or chelating coordination mode is described. The metalation procedure and the triazolylidene N-substituents determine the type of product obtained.
Sofia Friães; Sara Realista; Clara S. B. Gomes; Paulo N. Martinho; Luis F. Veiros; Martin Albrecht; Beatriz Royo. Manganese complexes with chelating and bridging di-triazolylidene ligands: synthesis and reactivity. Dalton Transactions 2021, 50, 5911 -5920.
AMA StyleSofia Friães, Sara Realista, Clara S. B. Gomes, Paulo N. Martinho, Luis F. Veiros, Martin Albrecht, Beatriz Royo. Manganese complexes with chelating and bridging di-triazolylidene ligands: synthesis and reactivity. Dalton Transactions. 2021; 50 (17):5911-5920.
Chicago/Turabian StyleSofia Friães; Sara Realista; Clara S. B. Gomes; Paulo N. Martinho; Luis F. Veiros; Martin Albrecht; Beatriz Royo. 2021. "Manganese complexes with chelating and bridging di-triazolylidene ligands: synthesis and reactivity." Dalton Transactions 50, no. 17: 5911-5920.
The reaction of coordinatively unsaturated Co(II) PCP pincer complexes with nitric oxide leads to the formation of new, air-stable, diamagnetic mono nitrosyl compounds. The synthesis and characterization of five- and four-coordinate Co(III) and Co(I) nitrosyl pincer complexes based on three different ligand scaffolds is described. Passing NO through a solution of [Co(PCPNMe-iPr)Cl], [Co(PCPO-iPr)Cl] or [Co(PCPCH2-iPr)Br] led to the formation of the low-spin complex [Co(PCP-iPr)(NO)X] with a strongly bent NO ligand. Treatment of the latter species with (X = Cl, Br) AgBF4 led to chloride abstraction and formation of cationic square-planar Co(I) complexes of the type [Co(PCP-iPr)(NO)]+ featuring a linear NO group. This reaction could be viewed as a formal two electron reduction of the metal center by the NO radical from Co(III) to Co(I), if NO is counted as NO+. Hence, these systems can be described as {CoNO}8 according to the Enemark–Feltham convention. X-ray structures, spectroscopic and electrochemical data of all nitrosyl complexes are presented. Preliminary studies show that [Co(PCPNMe-iPr)(NO)]+ catalyzes efficiently the reductive hydroboration of nitriles with pinacolborane (HBpin) forming an intermediate {CoNO}8 hydride species.
Jan Pecak; Wolfgang Eder; Berthold Stöger; Sara Realista; Paulo N. Martinho; Maria José Calhorda; Wolfgang Linert; Karl Kirchner. Synthesis, Characterization, and Catalytic Reactivity of {CoNO}8 PCP Pincer Complexes. Organometallics 2020, 39, 2594 -2601.
AMA StyleJan Pecak, Wolfgang Eder, Berthold Stöger, Sara Realista, Paulo N. Martinho, Maria José Calhorda, Wolfgang Linert, Karl Kirchner. Synthesis, Characterization, and Catalytic Reactivity of {CoNO}8 PCP Pincer Complexes. Organometallics. 2020; 39 (14):2594-2601.
Chicago/Turabian StyleJan Pecak; Wolfgang Eder; Berthold Stöger; Sara Realista; Paulo N. Martinho; Maria José Calhorda; Wolfgang Linert; Karl Kirchner. 2020. "Synthesis, Characterization, and Catalytic Reactivity of {CoNO}8 PCP Pincer Complexes." Organometallics 39, no. 14: 2594-2601.
The capability of a given substance to change its spin state by the action of a stimulus, such as a change in temperature, is by itself a very challenging property. Its interest is increased by the potential applications and the need to find sustainable functional materials. 3D transition metal complexes, mainly with octahedral geometry, display this property when coordinated to particular sets of ligands. The prediction of this behavior has been attempted by many authors. It is, however, made very difficult because spin crossover (SCO), as it is called, occurs most often in the solid state, where besides complexes, counter ions, and solvents are also present in many cases. Intermolecular interactions definitely play a major role in SCO. In this review, we decided to analyze SCO in mono- and binuclear transition metal complexes containing halogens as ligands or as substituents of the ligands. The aim was to try and find trends in the properties which might be correlated to halogen substitution patterns. Besides a revision of the properties, we analyzed structures and other information. We also tried to build a simple model to run Density Functional Theory (DFT) calculations and calculate several parameters hoping to find correlations between calculated indices and SCO data. Although there are many experimental studies and single-crystal X-ray diffraction structures, there are only few examples with the F, Cl, Br and series. When their intermolecular interactions were not very different, T1/2 (temperature with 50% high spin and 50% low spin states) usually increased with the calculated ligand field parameter (Δoct) within a given family. A way to predict SCO remains elusive.
Paulo N. Martinho; Frederico F. Martins; Nuno A. G. Bandeira; Maria José Calhorda. Spin Crossover in 3D Metal Centers Binding Halide-Containing Ligands: Magnetism, Structure and Computational Studies. Sustainability 2020, 12, 2512 .
AMA StylePaulo N. Martinho, Frederico F. Martins, Nuno A. G. Bandeira, Maria José Calhorda. Spin Crossover in 3D Metal Centers Binding Halide-Containing Ligands: Magnetism, Structure and Computational Studies. Sustainability. 2020; 12 (6):2512.
Chicago/Turabian StylePaulo N. Martinho; Frederico F. Martins; Nuno A. G. Bandeira; Maria José Calhorda. 2020. "Spin Crossover in 3D Metal Centers Binding Halide-Containing Ligands: Magnetism, Structure and Computational Studies." Sustainability 12, no. 6: 2512.
Sara Realista; Janaína C. Almeida; Sofia A. Milheiro; Nuno A. G. Bandeira; Luis G. Alves; Filipe Madeira; Maria José Calhorda; Paulo N. Martinho. Cover Feature: Co II Cryptates Convert CO 2 into CO and CH 4 under Visible Light (Chem. Eur. J. 50/2019). Chemistry – A European Journal 2019, 25, 11583 -11583.
AMA StyleSara Realista, Janaína C. Almeida, Sofia A. Milheiro, Nuno A. G. Bandeira, Luis G. Alves, Filipe Madeira, Maria José Calhorda, Paulo N. Martinho. Cover Feature: Co II Cryptates Convert CO 2 into CO and CH 4 under Visible Light (Chem. Eur. J. 50/2019). Chemistry – A European Journal. 2019; 25 (50):11583-11583.
Chicago/Turabian StyleSara Realista; Janaína C. Almeida; Sofia A. Milheiro; Nuno A. G. Bandeira; Luis G. Alves; Filipe Madeira; Maria José Calhorda; Paulo N. Martinho. 2019. "Cover Feature: Co II Cryptates Convert CO 2 into CO and CH 4 under Visible Light (Chem. Eur. J. 50/2019)." Chemistry – A European Journal 25, no. 50: 11583-11583.
Three Co(II) octaazacryptates, with different substituents on the aromatic rings (Br, NO₂, CCH), were synthesised and characterised. These and the already published non‐substituted cryptate catalysed CO₂ photoreduction to CO and CH₄ under blue visible‐light at room temperature. While CO was observed after short irradiation times and a large range of catalyst concentration, CH₄ was only observed after longer irradiation periods, such as 30 h, but with small catalyst concentration (25 nM). Experiments with ¹³C labelled CO showed that CO is formed and reacts further when the reaction time is long. The CCH catalyst is deactivated faster than the others and the more efficient catalyst for CH₄ production is the one with Br. This reactivity trend was explained by an Energy Decomposition Analysis based on DFT calculations.
Sara Realista; Janaína C. Almeida; Sofia A. Milheiro; Nuno Bandeira; Luis Alves; Filipe Madeira; Maria José Calhorda; Paulo N. Martinho. Co II Cryptates Convert CO 2 into CO and CH 4 under Visible Light. Chemistry – A European Journal 2019, 25, 11670 -11679.
AMA StyleSara Realista, Janaína C. Almeida, Sofia A. Milheiro, Nuno Bandeira, Luis Alves, Filipe Madeira, Maria José Calhorda, Paulo N. Martinho. Co II Cryptates Convert CO 2 into CO and CH 4 under Visible Light. Chemistry – A European Journal. 2019; 25 (50):11670-11679.
Chicago/Turabian StyleSara Realista; Janaína C. Almeida; Sofia A. Milheiro; Nuno Bandeira; Luis Alves; Filipe Madeira; Maria José Calhorda; Paulo N. Martinho. 2019. "Co II Cryptates Convert CO 2 into CO and CH 4 under Visible Light." Chemistry – A European Journal 25, no. 50: 11670-11679.
Particles with different sizes promote spin crossover at 220 K and a 10 K hysteresis.
Ana I. Vicente; Xinwey Wu; Yannick Ortin; Liliana Maria Pires Ferreira; Maria De Deus Carvalho; Sara Realista; Andrew Barker; Grace Genevieve Morgan; Nuno Galamba; Paulo J. Costa; Maria Jose Calhorda; Paulo N. Martinho; Xinwei Wu. Directing self-assembly in solution towards improved cooperativity in Fe(iii) complexes with amphiphilic tridentate ligands. Dalton Transactions 2019, 48, 4239 -4247.
AMA StyleAna I. Vicente, Xinwey Wu, Yannick Ortin, Liliana Maria Pires Ferreira, Maria De Deus Carvalho, Sara Realista, Andrew Barker, Grace Genevieve Morgan, Nuno Galamba, Paulo J. Costa, Maria Jose Calhorda, Paulo N. Martinho, Xinwei Wu. Directing self-assembly in solution towards improved cooperativity in Fe(iii) complexes with amphiphilic tridentate ligands. Dalton Transactions. 2019; 48 (13):4239-4247.
Chicago/Turabian StyleAna I. Vicente; Xinwey Wu; Yannick Ortin; Liliana Maria Pires Ferreira; Maria De Deus Carvalho; Sara Realista; Andrew Barker; Grace Genevieve Morgan; Nuno Galamba; Paulo J. Costa; Maria Jose Calhorda; Paulo N. Martinho; Xinwei Wu. 2019. "Directing self-assembly in solution towards improved cooperativity in Fe(iii) complexes with amphiphilic tridentate ligands." Dalton Transactions 48, no. 13: 4239-4247.
The new iron(III) complex [Fe(5‐I‐salEen)2]ClO4 exhibits both spin crossover, with hysteresis, between 304 K and 320 K (16 K hysteresis loop), and thermosalient phenomena. After a symmetry‐breaking phase transition between 120 and 130 K, confirmed by single‐crystal X‐ray diffraction, and the fragmentation of the crystals around 312 K, confirmed by differential scanning calorimetry and hot stage microscopy, the hysteresis loop disappears. This is the first example where the explicitly reported thermosalient effect modifies the magnetic properties of a given spin crossover crystal.
Frederico F. Martins; Abhinav Joseph; Herminio Diogo; Manuel E. Minas Da Piedade; Liliana Maria Pires Ferreira; Maria Deus Carvalho; Sonia Barroso; Maria João Romão; Maria José Calhorda; Paulo N. Martinho. Irreversible Magnetic Behaviour Caused by the Thermosalient Phenomenon in an Iron(III) Spin Crossover Complex. European Journal of Inorganic Chemistry 2018, 2018, 2976 -2983.
AMA StyleFrederico F. Martins, Abhinav Joseph, Herminio Diogo, Manuel E. Minas Da Piedade, Liliana Maria Pires Ferreira, Maria Deus Carvalho, Sonia Barroso, Maria João Romão, Maria José Calhorda, Paulo N. Martinho. Irreversible Magnetic Behaviour Caused by the Thermosalient Phenomenon in an Iron(III) Spin Crossover Complex. European Journal of Inorganic Chemistry. 2018; 2018 (25):2976-2983.
Chicago/Turabian StyleFrederico F. Martins; Abhinav Joseph; Herminio Diogo; Manuel E. Minas Da Piedade; Liliana Maria Pires Ferreira; Maria Deus Carvalho; Sonia Barroso; Maria João Romão; Maria José Calhorda; Paulo N. Martinho. 2018. "Irreversible Magnetic Behaviour Caused by the Thermosalient Phenomenon in an Iron(III) Spin Crossover Complex." European Journal of Inorganic Chemistry 2018, no. 25: 2976-2983.
Two polymorphic species of the [Fe(5-Br-salEen)2]ClO4 compound were obtained, each of them being selectively recovered after evaporation of the solvent at a controlled rate.
Ana I. Vicente; Liliana Maria Pires Ferreira; Maria De Deus Carvalho; Vitor Rodrigues; Marinela M. Dîrtu; Yann Garcia; Maria José Calhorda; Paulo N. Martinho. Selecting the spin crossover profile with controlled crystallization of mononuclear Fe(iii) polymorphs. Dalton Transactions 2018, 47, 7013 -7019.
AMA StyleAna I. Vicente, Liliana Maria Pires Ferreira, Maria De Deus Carvalho, Vitor Rodrigues, Marinela M. Dîrtu, Yann Garcia, Maria José Calhorda, Paulo N. Martinho. Selecting the spin crossover profile with controlled crystallization of mononuclear Fe(iii) polymorphs. Dalton Transactions. 2018; 47 (20):7013-7019.
Chicago/Turabian StyleAna I. Vicente; Liliana Maria Pires Ferreira; Maria De Deus Carvalho; Vitor Rodrigues; Marinela M. Dîrtu; Yann Garcia; Maria José Calhorda; Paulo N. Martinho. 2018. "Selecting the spin crossover profile with controlled crystallization of mononuclear Fe(iii) polymorphs." Dalton Transactions 47, no. 20: 7013-7019.
Several ferrocene derivatives (five mononuclear and two binuclear), including the new N-(p-chlorophenyl)-carboxamidoferrocene (1), were synthesized and their anticancer activity investigated. Two of them, 3 and 7, bearing a benzimidazole backbone were the most active against HeLa cells achieving IC50 values of ~5 μM along with 4 with a dipyridylamine ligand (~6 μM). Complex 6, also with a benzimidazole backbone, displayed slightly higher values (~11 μM). Cyclic voltammetry studies show that while the non-cytotoxic ferrocene derivatives 1, 2, and 5 follow a ferrocene-based redox behavior, derivatives 3, 4, 6, and 7 exhibit a more complex mechanism. These complex mechanisms are consistent with a more effective cytotoxic activity. Mössbauer spectroscopy parameters reflect a very small influence of the substituents.
Sara Realista; Susana Quintal; Paulo N. Martinho; Ana Isabel Melato; Adrià Gil; Teresa Esteves; Maria Deus Carvalho; Liliana Maria Pires Ferreira; Pedro D. Vaz; Maria Jose' Calhorda. Electrochemical studies and potential anticancer activity in ferrocene derivatives. Journal of Coordination Chemistry 2016, 70, 314 -327.
AMA StyleSara Realista, Susana Quintal, Paulo N. Martinho, Ana Isabel Melato, Adrià Gil, Teresa Esteves, Maria Deus Carvalho, Liliana Maria Pires Ferreira, Pedro D. Vaz, Maria Jose' Calhorda. Electrochemical studies and potential anticancer activity in ferrocene derivatives. Journal of Coordination Chemistry. 2016; 70 (2):314-327.
Chicago/Turabian StyleSara Realista; Susana Quintal; Paulo N. Martinho; Ana Isabel Melato; Adrià Gil; Teresa Esteves; Maria Deus Carvalho; Liliana Maria Pires Ferreira; Pedro D. Vaz; Maria Jose' Calhorda. 2016. "Electrochemical studies and potential anticancer activity in ferrocene derivatives." Journal of Coordination Chemistry 70, no. 2: 314-327.
Single ion magnet behaviour is reported for a mononuclear Mn(iii) ion with tridentate Schiff-base ligands revealing that the size of the axial anisotropy is the highest reported to date.
S. Realista; A. J. Fitzpatrick; G. Santos; L. P. Ferreira; S. Barroso; L. C. J. Pereira; N. A. G. Bandeira; P. Neugebauer; J. Hrubý; G. G. Morgan; J. Van Slageren; M. J. Calhorda; P. N. Martinho. A Mn(iii) single ion magnet with tridentate Schiff-base ligands. Dalton Transactions 2016, 45, 12301 -12307.
AMA StyleS. Realista, A. J. Fitzpatrick, G. Santos, L. P. Ferreira, S. Barroso, L. C. J. Pereira, N. A. G. Bandeira, P. Neugebauer, J. Hrubý, G. G. Morgan, J. Van Slageren, M. J. Calhorda, P. N. Martinho. A Mn(iii) single ion magnet with tridentate Schiff-base ligands. Dalton Transactions. 2016; 45 (31):12301-12307.
Chicago/Turabian StyleS. Realista; A. J. Fitzpatrick; G. Santos; L. P. Ferreira; S. Barroso; L. C. J. Pereira; N. A. G. Bandeira; P. Neugebauer; J. Hrubý; G. G. Morgan; J. Van Slageren; M. J. Calhorda; P. N. Martinho. 2016. "A Mn(iii) single ion magnet with tridentate Schiff-base ligands." Dalton Transactions 45, no. 31: 12301-12307.
New hetero- and homo-dinuclear Cu/Ni complexes electropolymerise potentiodynamically on glassy carbon electrodes and the polymers reduce dioxygen in water. New Cu( ii )/Ni( ii ) heterodinuclear complexes with salphen-type ligands were synthesised via a stepwise template method. DFT studies were performed to understand their electronic properties, showing localisation of the HOMO on the Ni( ii ) fragment, while in the oxidised species the spin density was high at some carbon phenolate atoms. These new complexes were potentiodynamically electropolymerised on glassy carbon and platinum. Atomic force microscopy was used to evaluate the influence of the metal centres on the morphology of the polymers, revealing how the presence of Cu( ii ) increased the surface roughness. The oxygen reduction reaction was observed on both glassy carbon and platinum modified electrodes in neutral medium.
Sara Realista; Priscila Ramgi; Bernardo De P. Cardoso; Ana I. Melato; Ana S. Viana; Maria José Calhorda; Paulo N. Martinho. Heterodinuclear Ni( ii ) and Cu( ii ) Schiff base complexes and their activity in oxygen reduction. Dalton Transactions 2016, 45, 14725 -14733.
AMA StyleSara Realista, Priscila Ramgi, Bernardo De P. Cardoso, Ana I. Melato, Ana S. Viana, Maria José Calhorda, Paulo N. Martinho. Heterodinuclear Ni( ii ) and Cu( ii ) Schiff base complexes and their activity in oxygen reduction. Dalton Transactions. 2016; 45 (37):14725-14733.
Chicago/Turabian StyleSara Realista; Priscila Ramgi; Bernardo De P. Cardoso; Ana I. Melato; Ana S. Viana; Maria José Calhorda; Paulo N. Martinho. 2016. "Heterodinuclear Ni( ii ) and Cu( ii ) Schiff base complexes and their activity in oxygen reduction." Dalton Transactions 45, no. 37: 14725-14733.
Dynamic spin interchange where crystals explode with preservation of magnetic memory is observed for a mononuclear hysteretic Fe(iii) Schiff-base compound.
Ana I. Vicente; Abhinav Joseph; Liliana Maria Pires Ferreira; Maria De Deus Carvalho; Vítor H. N. Rodrigues; Mathieu Duttine; Hermínio P. Diogo; Manuel E. Minas Da Piedade; Maria José Calhorda; Paulo N. Martinho. Dynamic spin interchange in a tridentate Fe(iii) Schiff-base compound. Chemical Science 2016, 7, 4251 -4258.
AMA StyleAna I. Vicente, Abhinav Joseph, Liliana Maria Pires Ferreira, Maria De Deus Carvalho, Vítor H. N. Rodrigues, Mathieu Duttine, Hermínio P. Diogo, Manuel E. Minas Da Piedade, Maria José Calhorda, Paulo N. Martinho. Dynamic spin interchange in a tridentate Fe(iii) Schiff-base compound. Chemical Science. 2016; 7 (7):4251-4258.
Chicago/Turabian StyleAna I. Vicente; Abhinav Joseph; Liliana Maria Pires Ferreira; Maria De Deus Carvalho; Vítor H. N. Rodrigues; Mathieu Duttine; Hermínio P. Diogo; Manuel E. Minas Da Piedade; Maria José Calhorda; Paulo N. Martinho. 2016. "Dynamic spin interchange in a tridentate Fe(iii) Schiff-base compound." Chemical Science 7, no. 7: 4251-4258.
Anthony J. Fitzpatrick; Paulo N. Martinho; Brendan J. Gildea; John D. Holbrey; Grace G. Morgan. Robust Room Temperature Hysteresis in an FeIIISpin Crossover Metallomesogen. European Journal of Inorganic Chemistry 2015, 2016, 2025 -2029.
AMA StyleAnthony J. Fitzpatrick, Paulo N. Martinho, Brendan J. Gildea, John D. Holbrey, Grace G. Morgan. Robust Room Temperature Hysteresis in an FeIIISpin Crossover Metallomesogen. European Journal of Inorganic Chemistry. 2015; 2016 (13-14):2025-2029.
Chicago/Turabian StyleAnthony J. Fitzpatrick; Paulo N. Martinho; Brendan J. Gildea; John D. Holbrey; Grace G. Morgan. 2015. "Robust Room Temperature Hysteresis in an FeIIISpin Crossover Metallomesogen." European Journal of Inorganic Chemistry 2016, no. 13-14: 2025-2029.
Bernardo Rosa Lourenço De Pina Cardoso; Ana Vicente; Joseph B.J. Ward; Pedro J. Sebastião; Fabian Vaca Chavez; Sónia Barroso; Alexandra Carvalho; Stephen Keely; Paulo Martinho; Maria Jose' Calhorda. Fe(III) salEen derived Schiff base complexes as potential contrast agents. Inorganica Chimica Acta 2015, 432, 258 -266.
AMA StyleBernardo Rosa Lourenço De Pina Cardoso, Ana Vicente, Joseph B.J. Ward, Pedro J. Sebastião, Fabian Vaca Chavez, Sónia Barroso, Alexandra Carvalho, Stephen Keely, Paulo Martinho, Maria Jose' Calhorda. Fe(III) salEen derived Schiff base complexes as potential contrast agents. Inorganica Chimica Acta. 2015; 432 ():258-266.
Chicago/Turabian StyleBernardo Rosa Lourenço De Pina Cardoso; Ana Vicente; Joseph B.J. Ward; Pedro J. Sebastião; Fabian Vaca Chavez; Sónia Barroso; Alexandra Carvalho; Stephen Keely; Paulo Martinho; Maria Jose' Calhorda. 2015. "Fe(III) salEen derived Schiff base complexes as potential contrast agents." Inorganica Chimica Acta 432, no. : 258-266.
We use electrochemistry to polymerise the new asymmetric binuclear Cu(ii)/Cu(ii) and Ni(ii)/Ni(ii) monomers and study their behaviour as modified electrodes.
Sara Realista; Ana S. Viana; Bernardo De P. Cardoso; Ana M. Botelho Do Rego; Pedro D. Vaz; Ana I. Melato; Paulo N. Martinho; Maria José Calhorda. Asymmetric binuclear Ni(ii) and Cu(ii) Schiff base metallopolymers. RSC Advances 2015, 5, 39495 -39504.
AMA StyleSara Realista, Ana S. Viana, Bernardo De P. Cardoso, Ana M. Botelho Do Rego, Pedro D. Vaz, Ana I. Melato, Paulo N. Martinho, Maria José Calhorda. Asymmetric binuclear Ni(ii) and Cu(ii) Schiff base metallopolymers. RSC Advances. 2015; 5 (49):39495-39504.
Chicago/Turabian StyleSara Realista; Ana S. Viana; Bernardo De P. Cardoso; Ana M. Botelho Do Rego; Pedro D. Vaz; Ana I. Melato; Paulo N. Martinho; Maria José Calhorda. 2015. "Asymmetric binuclear Ni(ii) and Cu(ii) Schiff base metallopolymers." RSC Advances 5, no. 49: 39495-39504.
We investigate if the functionality of spin crossover molecules is preserved when they are assembled into an interfacial device structure. Specifically, we prepare and investigate gold nanoparticle arrays, into which room-temperature spin crossover molecules are introduced, more precisely, [Fe(AcS-BPP)2](ClO4)2, where AcS-BPP = (S)-(4-{[2,6-(dipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl)ethanethioate (in short, Fe(S-BPP)2). We combine three complementary experiments to characterize the molecule-nanoparticle structure in detail. Temperature-dependent Raman measurements provide direct evidence for a (partial) spin transition in the Fe(S-BPP)2-based arrays. This transition is qualitatively confirmed by magnetization measurements. Finally, charge transport measurements on the Fe(S-BPP)2-gold nanoparticle devices reveal a minimum in device resistance versus temperature, R(T), curves around 260-290 K. This is in contrast to similar networks containing passive molecules only that show monotonically decreasing R(T) characteristics. Backed by density functional theory calculations on single molecular conductance values for both spin states, we propose to relate the resistance minimum in R(T) to a spin transition under the hypothesis that (1) the molecular resistance of the high spin state is larger than that of the low spin state and (2) transport in the array is governed by a percolation model.
Edwin J. Devid; Paulo Martinho; M. Venkata Kamalakar; Ivan Šalitroš; Una Prendergast; Jean Francois Dayen; Velimir Meded; Tibebe Lemma; Rodrigo González-Prieto; Ferdinand Evers; Tia Keyes; Mario Ruben; Bernard Doudin; Sense Jan van der Molen. Spin Transition in Arrays of Gold Nanoparticles and Spin Crossover Molecules. ACS Nano 2015, 9, 4496 -4507.
AMA StyleEdwin J. Devid, Paulo Martinho, M. Venkata Kamalakar, Ivan Šalitroš, Una Prendergast, Jean Francois Dayen, Velimir Meded, Tibebe Lemma, Rodrigo González-Prieto, Ferdinand Evers, Tia Keyes, Mario Ruben, Bernard Doudin, Sense Jan van der Molen. Spin Transition in Arrays of Gold Nanoparticles and Spin Crossover Molecules. ACS Nano. 2015; 9 (4):4496-4507.
Chicago/Turabian StyleEdwin J. Devid; Paulo Martinho; M. Venkata Kamalakar; Ivan Šalitroš; Una Prendergast; Jean Francois Dayen; Velimir Meded; Tibebe Lemma; Rodrigo González-Prieto; Ferdinand Evers; Tia Keyes; Mario Ruben; Bernard Doudin; Sense Jan van der Molen. 2015. "Spin Transition in Arrays of Gold Nanoparticles and Spin Crossover Molecules." ACS Nano 9, no. 4: 4496-4507.
We prepare and investigate two-dimensional (2D) single-layer arrays and multilayered networks of gold nanoparticles derivatized with conjugated hetero-aromatic molecules, i.e., S-(4-{[2,6-bipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl)thiolate (herein S-BPP), as capping ligands. These structures are fabricated by a combination of self-assembly and microcontact printing techniques, and are characterized by electron microscopy, UV–visible spectroscopy and Raman spectroscopy. Selective binding of the S-BPP molecules to the gold nanoparticles through Au–S bonds is found, with no evidence for the formation of N–Au bonds between the pyridine or pyrazole groups of BPP and the gold surface. Subtle, but significant shifts with temperature of specific Raman S-BPP modes are also observed. We attribute these to dynamic changes in the orientation and/or increased mobility of the molecules on the gold nanoparticle facets. As for their conductance, the temperature-dependence for S-BPP networks differs significantly from standard alkanethiol-capped networks, especially above 220 K. Relating the latter two observations, we propose that dynamic changes in the molecular layers effectively lower the molecular tunnel barrier for BPP-based arrays at higher temperatures.
Edwin J. Devid; Paulo Martinho; M. Venkata Kamalakar; Úna Prendergast; Christian Kübel; Tibebe Lemma; Jean Francois Dayen; Tia. E. Keyes; Bernard Doudin; Mario Ruben; Sense Jan van der Molen. The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands. Beilstein Journal of Nanotechnology 2014, 5, 1664 -1674.
AMA StyleEdwin J. Devid, Paulo Martinho, M. Venkata Kamalakar, Úna Prendergast, Christian Kübel, Tibebe Lemma, Jean Francois Dayen, Tia. E. Keyes, Bernard Doudin, Mario Ruben, Sense Jan van der Molen. The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands. Beilstein Journal of Nanotechnology. 2014; 5 (1):1664-1674.
Chicago/Turabian StyleEdwin J. Devid; Paulo Martinho; M. Venkata Kamalakar; Úna Prendergast; Christian Kübel; Tibebe Lemma; Jean Francois Dayen; Tia. E. Keyes; Bernard Doudin; Mario Ruben; Sense Jan van der Molen. 2014. "The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands." Beilstein Journal of Nanotechnology 5, no. 1: 1664-1674.
The mono-dentate, pyridyl containing, nitro naphthalimide ligands N-(4-pyridyl)-4-nitro-1,8-naphthalimide (L1) and N-(3-pyridyl)-4-nitro-1,8-naphthalimide (L2) were prepared and complexed with a selection of copper salts [Cu(OAc)2, Cu(CF3SO3)2 and Cu(ClO4)2]. Crystallographic studies were undertaken and revealed that dinuclear acetate bridged complexes resulted from reactions with Cu(OAc)2, while mononuclear systems resulted from reactions with Cu(CF3SO3)2 and Cu(ClO4)2. Despite the differing coordination environments the naphthalimide based ligands provided a range of interesting π-based interactions in the form of ππ, anionπ, nitroπ, solventπ and COπ associations. Solid state EPR spectra were in agreement with the coordination environments observed from crystallography.
Jonathan A. Kitchen; Paulo N. Martinho; Grace G. Morgan; Thorfinnur Gunnlaugsson. Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands. Dalton Transactions 2014, 43, 6468 -6479.
AMA StyleJonathan A. Kitchen, Paulo N. Martinho, Grace G. Morgan, Thorfinnur Gunnlaugsson. Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands. Dalton Transactions. 2014; 43 (17):6468-6479.
Chicago/Turabian StyleJonathan A. Kitchen; Paulo N. Martinho; Grace G. Morgan; Thorfinnur Gunnlaugsson. 2014. "Synthesis, crystal structure and EPR spectroscopic analysis of novel copper complexes formed from N-pyridyl-4-nitro-1,8-naphthalimide ligands." Dalton Transactions 43, no. 17: 6468-6479.
The effect of the phenolate ring derivatisation on the magnetic properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands both in solid state and solution have been investigated. Two new complexes [Fe(3,5-Br-salEen)2]ClO4.EtOH (5) and [Fe(3,5-Br-salEen)2]BPh4.DMF (6) have been synthesised. SQUID magnetometry studies on these complexes showed that while complex 5 is in the low-spin (LS) state, complex 6 displays a gradual and incomplete spin crossover (SCO) transition over the temperature measured. Solution measurements on a series of six complexes – [Fe(salEen)2]ClO4 (1), [Fe(salEen)2]BPh4·0.5H2O (2), [Fe(5-Br-salEen)2]ClO4 (3), [Fe(5-Br-salEen)2]BPh4·DMF (4), [Fe(3,5-Br-salEen)2]ClO4·EtOH (5) and [Fe(3,5-Br-salEen)2]BPh4·DMF (6) – were performed by UV–vis and NMR spectroscopies and cyclic voltammetry. Solution studies show that the presence of electron withdrawing groups (bromine atoms) affect the electronic density at the phenolate ring, thus influencing the ligand field strength and the separation between the t2g and eg* energy levels. The presence of two bromide substituents at the phenolate ring has a more pronounced effect on the magnetic behaviour in solution than in the solid state, with both complexes 5 and 6 adopting preferentially the LS state. Electrochemical studies of complexes 1–6 reveal that the reduction of the metallic centres in the complexes with electron withdrawing groups is easier, with E1/2 values of iron moving to more positive potentials with the number of bromide substituents at the phenolate ring.
Paulo N. Martinho; Ana I. Vicente; Sara Realista; Marta S. Saraiva; Ana I. Melato; Paula Brandão; Liliana P. Ferreira; Maria De Deus Carvalho. Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands. Journal of Organometallic Chemistry 2013, 760, 48 -54.
AMA StylePaulo N. Martinho, Ana I. Vicente, Sara Realista, Marta S. Saraiva, Ana I. Melato, Paula Brandão, Liliana P. Ferreira, Maria De Deus Carvalho. Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands. Journal of Organometallic Chemistry. 2013; 760 ():48-54.
Chicago/Turabian StylePaulo N. Martinho; Ana I. Vicente; Sara Realista; Marta S. Saraiva; Ana I. Melato; Paula Brandão; Liliana P. Ferreira; Maria De Deus Carvalho. 2013. "Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands." Journal of Organometallic Chemistry 760, no. : 48-54.