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001-es BibID:	BIBFORM100007
035-os BibID:	(WoS)000739628200001 (Scopus)85123758171
Első szerző:	Pérez-Lourido, Paulo
Cím:	Stable and inert macrocyclic cobalt(II) and nickel(II) complexes with paraCEST response / Paulo Pérez-Lourido, Enikő Madarasi, Fanni Antal, David Esteban-Gómez, Gaoji Wang, Goran Angelovski, Carlos Platas-Iglesias, Gyula Tircsó, Laura Valencia
Dátum:	2022
ISSN:	1477-9226
Megjegyzések:	We report the synthesis of the macrocyclic ligands 3,9 PC2AMH (2,2'-(3,6,9-triaza-1(2,6)-pyridinacyclodecaphane-3,9-diyl)diacetamide) and 3,9-PC2AMtBu (2,2'-(3,6,9-triaza-1(2,6)-pyridinacyclodecaphane-3,9-diyl)bis(N-tert-butyl)acetamide) which contain a pyclen platform functionalized with acetamide or tert-butylacetamide pendant arms at positions 3 and 9 of the macrocyclic unit. The corresponding Co(II) and Ni(II) complexes were prepared, isolated and characterised as potential paramagnetic chemical exchange saturation transfer (paraCEST) agents. The X-ray structures of the Ni(II) complexes reveal six-coordination of the ligands to the metal ion. The Co(II) complex with 3,9-PC2AMtBu shows a similar six-coordinate structure in the solid state, while the Co(II) complex with 3,9 PC2AMH contains a seven-coordinate metal ion, seventh coordination being completed by the presence of an inner-sphere water molecule. The structure of the Co(II) complexes was investigated using 1H NMR spectroscopy and computational methods. The complexes present a seven-coordinate structure in solution, as demonstrated by the analysis of the paramagnetic shifts using density functional theory. Ligand protonation constants and stability constants of the complexes with 3,9 PC2AMH were determined using potentiometric titrations (I=0,15 M NaCl). The Co(II) complex was found to be more stable than the Ni(II) analogue (log KCoL = 14.46(5) and log KNiL = 13.15(3)). However, the Ni(II) and Co(II) complexes display similar rate constants characterizing the proton-assisted dissociation mechanism. The presence of highly shifted 1H NMR signals due to the amide protons in slow exchange with bulk water results in sizeable CEST signals, which are observed at +67 and +15 ppm for the Co(II) complex with 3,9 PC2AMH and +42 and +7 ppm for the Ni(II) analogue at 25 oC .
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk paraCEST PC2A-bis(amides) stability inertnes, structure
Megjelenés:	Dalton Transactions. - 51 : 4 (2022), p. 1580-1593. -
További szerzők:	Madarasi Enikő Antal Fanni Esteban-Gómez, David Wang, Gaoji Angelovski, Goran Platas-Iglesias, Carlos Tircsó Gyula (1977-) (vegyész, kémia tanár) Valencia, Laura
Pályázati támogatás:	K-120224 OTKA K-134694 OTKA Doctoral School of Chemistry at the University of Debrecen, Debrecen, Hungary Egyéb COST Action CA15209 "European Network on NMR Relaxometry Egyéb Bilateral Hungarian-Spanish Science and Technology Cooperation Program (2019-2.1.11- TET-2019-00084 supported by NKFIH). Egyéb
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001-es BibID:	BIBFORM067433
Első szerző:	Rodríguez-Rodríguez, Aurora
Cím:	Stable Mn2+, Cu2+ and Ln3+ complexes with cyclen-based ligands functionalized with picolinate pendant arms / Aurora Rodríguez-Rodríguez, Zoltán Garda, Erika Ruscsák, David Esteban-Gómez, Andrés de Blas, Teresa Rodríguez-Blas, Luís M. P. Lima, Maryline Beyler, Raphaël Tripier, Gyula Tircsó, Carlos Platas-Iglesias
Dátum:	2015
ISSN:	1477-9226
Megjegyzések:	In this study we present the results of the equilibrium, dissociation kinetics, DFT and X-ray crystallographic studies performed on the complexes of metal ions of biomedical importance (Mn2+, Cu2+ and Gd3+) formed with octadentate ligands based on a cyclen platform incorporating two picolinate pendant arms (dodpa2? and Medodpa2?). The stability constants of the complexes were accessed by multiple methods (pH-potentiometry, direct and competition UV-vis spectrophotometry and 1H-relaxometry). The stability constants of the complexes formed with dodpa2? and Medodpa2? do not differ significantly (e.g. log K[Mn(dodpa)] = 17.40 vs. log K[Mn(Medodpa)] = 17.46, log K[Cu(dodpa)] = 24.34?25.17 vs. log K[Cu(Medodpa)] = 24.74 and log K[Gd(dodpa)]+ = 17.27 vs. log K[Gd(Medodpa)]+ = 17.59), which indicates that the steric hindrance brought by the methyl groups has no significant effect on the stability of the complexes. The stability constants of the Mn2+ complexes formed with the cyclen dipicolinates were found to be ca. 3 log K units higher than those determined for the complex of the cyclen monopicolinate (dompa?), which indicates that the second picolinate moiety attached to the backbone of the macrocycle is very likely coordinated to the Mn2+ ion. However, the stability of the [Cu(dodpa)] and [Cu(Medodpa)] complexes agrees well with the stability constant of [Cu(dompa)]+, in line with the hexadentate coordination around the metal ion observed in the X-ray structure of [Cu(Medodpa)]. The [Gd(dodpa)]+ and [Gd(Medodpa)]+ complexes display a fairly high kinetic inertness, as the rate constants of acid catalysed dissociation (k1 = 2.5(4) ? 10?3 and 8.3(4) ? 10?4 M?1 s?1 for [Gd(dodpa)]+ and [Gd(Medodpa)]+, respectively) are smaller than the value reported for [Gd(do3a)] (k1 = 2.5 ? 10?2 M?1 s?1). The [Mn(dodpa)] complex was found to be more inert than [Mn(Medodpa)]. The results of the diffusion-ordered NMR spectroscopy (DOSY) and DFT calculations of diamagnetic [La(dodpa)]+ and [Lu(dodpa)]+ complexes indicate the formation of a trinuclear entity of the La complex in aqueous solution.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban cyclen-based ligand transition metal lanthanide picolinate pendant thermodynamic stability kinetic inertness
Megjelenés:	Dalton Transactions 44 (2015), p. 5017-5031. -
További szerzők:	Garda Zoltán (1989-) (vegyész) Ruscsák Erika (1989-) (vegyész) Esteban-Gómez, David Blas, Andrès de Rodríguez-Blas, Teresa Lima, Luís M. P. Beyler, Maryline Tripier, Raphaël Tircsó Gyula (1977-) (vegyész, kémia tanár) Platas-Iglesias, Carlos
Pályázati támogatás:	OTKA-84291 OTKA OTKA-109029 OTKA TÁMOP 4.2.2.A-11/1/KONV-2012-0043 TÁMOP János Bolyai Research Scholarship MTA COST TD1004 " Theragnostics Imaging and Therapy: An Action to Develop Novel Nano-sized Systems for Imaging-Guided Drug Delivery " Egyéb CM1006 European F-Element Network (EUFEN) Actions Egyéb
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001-es BibID:	BIBFORM103038
035-os BibID:	(wos)000481917100005 (scopus)85071026081
Első szerző:	Tircsó Gyula (vegyész, kémia tanár)
Cím:	Dialing in on pharmacological features for a therapeutic antioxidant small molecule / Green Kayla N., Pota Kristof, Tircsó Gyula, Gogolák Réka Anna, Kinsinger Olivia, Davda Collin, Blain Kimberly, Brewer Samantha M. Gonzalez Paulina, Johnston Hannah M., Akkaraju Giridhar
Dátum:	2019
ISSN:	1477-9226
Megjegyzések:	The pyridinophane molecule L2 (3,6,9,15-tetraazabicyclo[9.3.1]penta-deca-1(15),11,13-trien-13- ol) has shown promise as a therapuetic for neurodegenerative diseases involving oxidative stress and metal ion misregulation. Protonation and metal binding stability constants with Mg2+, Ca2+, Cu2+, and Zn2+ ions were determined to further explore the therapeutic and pharmacological potential of this water soluble small molecule. These studies show that incorporation of an ?OH group in position 4 of the pyridine ring decreases the pI values compared to cyclen and L1 (3,6,9,15-tetraazabicyclo[9.3.1]penta-deca-1(15),11,13-triene). Furthermore, this approach tunes the basicity of the tetra-aza macrocyclic ligand through the enhanced resonance stabilization of the ?OH in position 4 and rigidity of the pyridine ring such that L2 has increased basicity compared to previously reported tetra-aza macrocycles. A metal binding preference for Cu2+, a redox cycling agent known to produce oxidative stress, indicates that this would be the in vivo metal target of L2. However, the binding constant of L2 with Cu2+ is moderated compared to cyclen due to the rigidity of the ligand and shows how ligand design can be used to tune metal selectivity. An IC50=298.0 ?M in HT-22 neuronal cells was observed. Low metabolic liability was determined in both Phase I and II in vitro models. Throughout these studies other metal binding systems were used for comparison and as appropriate controls. The reactivity reported to date and pharmacological features described herein warrant further studies in vivo and the pursuit of L2 congeners using the knowledge that pyridine substitution in a pyridinophane can be used to tune the structure of the ligand and retain the positive therapeutic outcomes.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk Ligand Pyridinophane tetra-aza macrocycle binding transition metal-ion
Megjelenés:	Dalton Transactions. - 48 : 33 (2019), p. 12430-12439. -
További szerzők:	Green, Kayla N. Póta Kristóf Gogolák Réka Anna (kémia tanár) Olivia Kinsinger Collin Davda Kimberly Blaina Samantha M. Brewer Paulina Gonzalez Hannah M. Johnston Giridhar Akkarajuc
Pályázati támogatás:	(NKFIH K-120224) MTA ÚNKP-18?4 N Egyéb GINOP-2.3.2-15-2016-00008 GINOP GINOP-2.3.3-15-2016-00004 GINOP
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001-es BibID:	BIBFORM018830
Első szerző:	Woods, Mark
Cím:	Investigations into whole water, prototropic and amide proton exchange in lanthanide(iii) DOTA-tetraamide chelates / Mark Woods, Azhar Pasha, Piyu Zhao, Gyula Tircso, Somdatta Chowdhury, Garry Kiefer, Donald E. Woessner, A. Dean Sherry
Dátum:	2011
ISSN:	1477-9226
Megjegyzések:	Lanthanide(III) chelates of DOTA-tetraamide ligands have been an area of particular interest since the discovery that water exchange kinetics are dramatically affected by the switch from acetate to amide side-chain donors. More recently these chelates have attracted interest as potential PARACEST agents for use in MRI. In this paper we report the results of studies using chemical exchange saturation transfer (CEST) and some more recently reported chelates to re-examine the exchange processes in this class of chelate. We find that the conclusions of Parker and Aime are, for the most part, solid; water exchange is slow and a substantial amount of prototropic exchange occurs in aqueous solution. The extent of prototropic exchange increases as the pH increases above 8, leading to higher relaxivities at high pH. However, amide protons are found to contribute only a small amount to the relaxivity at high pH.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Dalton Transactions. - 40 : 25 (2011), p. 6759-6764. -
További szerzők:	Pasha, Azhar Zhao, Piyu Tircsó Gyula (1977-) (vegyész, kémia tanár) Chowdhury, Somdatta Kiefer, Garry E. Woessner, Donald E. Sherry, A. Dean
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