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001-es BibID:	BIBFORM076226
035-os BibID:	(WoS)000433013600028 (Scopus)85047315800
Első szerző:	Gündüz, Serhat
Cím:	Coordination Properties of GdDO3A-Based Model Compounds of Bioresponsive MRI Contrast Agents / Serhat Gündüz, Sandip Vibhute, Richard Botár, Ferenc K. Kálmán, Imre Tóth, Gyula Tircsó, Martín Regueiro-Figueroa, David Esteban-Gómez, Carlos Platas-Iglesias, Goran Angelovski
Dátum:	2018
ISSN:	0020-1669 1520-510X
Megjegyzések:	We report a detailed characterization of the thermodynamic stability and dissociation kinetics of Gd3+ complexes with DO3A derivatives containing a (methylethylcarbamoylmethylamino)acetic acid (L1), (methylpropylcarbamoylmethylamino)acetic acid (L2), 2-dimethylamino-N-ethylacetamide (L3), or 2-dimethylamino-N-propylacetamide (L4) group attached to the fourth nitrogen atom of the macrocyclic unit. These ligands are model systems of Ca2+- and Zn2+-responsive contrast agents (CA) for application in magnetic resonance imaging (MRI). The results of the potentiometric studies (I = 0.15 M NaCl) provide stability constants with log KGdL values in the range 13.9?14.8. The complex speciation in solution was found to be quite complicated due to the formation of protonated species at low pH, hydroxido complexes at high pH, and stable dinuclear complexes in the case of L1,2. At neutral pH significant fractions of the complexes are protonated at the amine group of the amide side chain (log KGdL?H = 7.2?8.1). These ligands form rather weak complexes with Mg2+ and Ca2+ but very stable complexes with Cu2+ (log KCuL = 20.4?22.3) and Zn2+ (log KZnL = 15.5?17.6). Structural studies using a combination of 1H NMR and luminescence spectroscopy show that the amide group of the ligand is coordinated to the metal ion at pH ?8.5, while protonation of the amine group provokes the decoordination of the amide O atom and a concomitant increase in the hydration number and proton relaxivity. The dissociation of the complexes occurs mainly through a rather efficient proton-assisted pathway, which results in kinetic inertness comparable to that of nonmacrocyclic ligands such as DTPA rather than DOTA-like complexes.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Inorganic Chemistry. - 57 : 10 (2018), p. 5973-5986. -
További szerzők:	Vibhute, Sandip Botár Richárd (1992-) (vegyész) Kálmán Ferenc K. (1978-) (vegyész) Tóth Imre (1950-) (vegyész) Tircsó Gyula (1977-) (vegyész, kémia tanár) Regueiro-Figueroa, Martín Esteban-Gómez, David Platas-Iglesias, Carlos Angelovski, Goran
Pályázati támogatás:	GINOP-2.3.2-15-2016-00008 GINOP GINOP-2.3.3-15-2016-00004 GINOP
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001-es BibID:	BIBFORM057619
Első szerző:	Regueiro-Figueroa, Martín
Cím:	Highly Stable Complexes of Divalent Metal Ions (Mg(II), Ca(II) , Cu(II), Zn(II), Cd(II), and Pb(II) with a Dota-Like Ligand Containing a Picolinate Pendant / Martín Regueiro-Figueroa, Erika Ruscsák, Laura Fra, Gyula Tircsó, Imre Tóth, Andrés de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias, David Esteban-Gómez
Dátum:	2014
ISSN:	1434-1948
Megjegyzések:	The stability constants of complexes of the macrocyclic liganddo3a-pic4? (H4do3a-pic = 2,2 ,2 -{10-[(6-carboxypyridin-2-yl)methyl]-1,4,7,10-tetraazacyclododecane-1,4,7-triyl}triacetic acid) with several divalent metal ions (Pb2+,Cd2+, Zn2+, Cu2+, Ca2+, and Mg2+) have been determined byusing pH-potentiometric titrations (I = 0.1 M KCl, 25 ?C). Thestability of these complexes follows the trend Cu2+ Cd2+?Pb2+?Zn2+ Ca2+ Mg2+. A particularly high stabilityconstant has been determined for the Cu2+ complex[logKCuL = 23.20(4)]. Analysis of the titration curves indicatethe presence of protonated forms of the complexes in solution,with protonation constants of logKM(HxL) = 6.9?2.0 (x =1, 2, or 3). The structure of the complexes in solution hasbeen investigated by using 1H and 13C NMR spectroscopyand DFT calculations performed in aqueous solution at theTPSSh/6-31G(d) level. In the case of the Pb2+ and Cd2+ complexes,relativistic effects were considered with the use ofrelativistic effective core potentials. Calculations show thatthe complexes with the largest metal ions (Pb2+ and Ca2+)are nine-coordinate, with their coordination polyhedra beingbest described as capped twisted square antiprisms. TheCd2+ and Mg2+ complexes are seven-coordinate, with themetal ions being bound to the four nitrogen atoms of the cyclenunit and the three acetate pendant arms. Finally, in theCu2+ and Zn2+ complexes, the metal ions are six-coordinated,with the metal ions being asymmetrically placed inside themacrocyclic cavity of the ligand, and the coordination polyhedracan be described as an octahedron and a trigonalprism, respectively.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Highly Stable Complexes DOTA-like ligands Picolinate Pendant
Megjelenés:	European Journal Of Inorganic Chemistry. - 2014 : 36 (2014), p. 6165-6173. -
További szerzők:	Ruscsák Erika (1989-) (vegyész) Fra, Laura Tircsó Gyula (1977-) (vegyész, kémia tanár) Tóth Imre (1950-) (vegyész) de Blas, Andrés Rodríguez-Blas, Teresa Platas-Iglesias, Carlos Esteban-Gómez, David
Pályázati támogatás:	Xunta de Galicia (CN 2012/011), (EM 2012/ 088) Egyéb Centro de Supercomputación de Galicia (CESGA) Egyéb K-84291 OTKA TÁMOP-4.2.2.A-11/1/KONV-2012-0043 TÁMOP János Bolyai Research Scholarship of the Hungarian Academy of Sciences Egyéb COST TD1004 "Theragnostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging-Guided Drug Delivery" Action. Egyéb
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001-es BibID:	BIBFORM018843
Első szerző:	Regueiro-Figueroa, Martín
Cím:	Lanthanide dota-like Complexes Containing a Picolinate Pendant: Structural Entry for the Design of LnIII-Based Luminescent Probes / Martín Regueiro-Figueroa, Bachir Bensenane, Erika Ruscsák, David Esteban-Gómez, Loïc J. Charbonnière, Gyula Tircsó, Imre Tóth, Andrès de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias
Dátum:	2011
ISSN:	0020-1669
Megjegyzések:	In this contribution we present two ligands based on a do3a platform containing a picolinate group attached to the fourth nitrogen atom of the cyclen unit, which are designed for stable lanthanide complexation in aqueous solutions. Potentiometric measurements reveal that the thermodynamic stability of the complexes is very high (log K = 21.2?23.5), being comparable to that of the dota analogues. Luminescence lifetime measurements performed on solutions of the EuIII and TbIII complexes indicate that the complexes are nine coordinate with no inner-sphere water molecules. A combination of density functional theory (DFT) calculations and NMR measurements shows that for the complexes of the heaviest lanthanides there is a major isomer in solution consisting of the enantiomeric pair ?(????) and ?(????), which provides square antiprismatic coordination (SAP) around the metal ion. Analysis of the YbIII-induced paramagnetic shifts unambiguously confirms that these complexes have SAP coordination in aqueous solution. For the light lanthanide ions however both the SAP and twisted-square antiprismatic (TSAP) isomers are present in solution. Inversion of the cyclen ring appears to be the rate-determining step for the ?(????) ? ?(????) enantiomerization process observed in the LuIII complexes. The energy barriers obtained from NMR measurements for this dynamic process are in excellent agreement with those predicted by DFT calculations. The energy barriers calculated for the arm-rotation process are considerably lower than those obtained for the ring-inversion path. Kinetic studies show that replacement of an acetate arm of dota by a picolinate pendant results in a 3-fold increase in the formation rate of the corresponding EuIII complexes and a significant increase of the rates of acid-catalyzed dissociation of the complexes. However, these rates are 1?2 orders of magnitude lower than those of do3a analogues, which shows that the complexes reported herein are remarkably inert with respect to metal ion dissociation.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban Molekulatudomány
Megjelenés:	Inorganic Chemistry. - 50 : 9 (2011), p. 4125-4141. -
További szerzők:	Bensenane, Bachir Ruscsák Erika (1989-) (vegyész) Esteban-Gómez, David Charbonnière, Loïc J. Tircsó Gyula (1977-) (vegyész, kémia tanár) Tóth Imre (1950-) (vegyész) Blas, Andrès de Rodríguez-Blas, Teresa Platas-Iglesias, Carlos
Pályázati támogatás:	TÁMOP-4.2.1/B-09/1/KONV-2010-0007 TÁMOP Ritkaföldfém munkacsoport
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001-es BibID:	BIBFORM067299
035-os BibID:	(WoS)000371753500032 (Scopus)84960430930
Első szerző:	Rodríguez-Rodríguez, Aurora
Cím:	Complexation of Ln3+ Ions with Cyclam Dipicolinates: A Small Bridge that Makes Huge Differences in Structure, Equilibrium, and Kinetic Properties / Aurora Rodríguez-Rodríguez, Martín Regueiro-Figueroa, David Esteban-Gómez, Raphaël Tripier, Gyula Tircsó, Ferenc Krisztián Kálmán, Attila Csaba Bényei, Imre Tóth, Andrés de Blas, Teresa Rodríguez-Blas, Carlos Platas-Iglesias
Dátum:	2016
ISSN:	0020-1669
Megjegyzések:	The coordination properties toward the lanthanide ions of two macrocyclic ligands based on a cyclam platform containing picolinate pendant arms have been investigated. The synthesis of the ligands was achieved by using the well-known bis-aminal chemistry. One of the cyclam derivatives (cb-tedpa2?) is reinforced with a cross-bridge unit, which results in exceptionally inert [Ln(cb-tedpa)]+ complexes. The X-ray structures of the [La(cb-tedpa)Cl], [Gd(cb-tedpa)]+, and [Lu(Me2tedpa)]+ complexes indicate octadentate binding of the ligands to the metal ions. The analysis of the Yb3+-induced shifts in [Yb(Me2tedpa)]+ indicates that this complex presents a solution structure very similar to that observed in the solid state for the Lu3+ analogue. The X-ray structures of [La(H2Me2tedpa)2]3+ and [Yb(H2Me2tedpa)2]3+ complexes confirm the exocyclic coordination of the metal ions, which gives rise to coordination polymers with the metal coordination environment being fulfilled by oxygen atoms of the picolinate groups and water molecules. The X-ray structure of [Gd(Hcb-tedpa)2]+ also indicates exocyclic coordination that in this case results in a discrete structure with an eight-coordinated metal ion. The nonreinforced complexes [Ln(Me2tedpa)]+ were prepared and isolated as chloride salts in nonaqueous media. However, these complexes were found to undergo dissociation in aqueous solution, except in the case of the complexes with the smallest Ln3+ ions (Ln3+ = Yb3+ and Lu3+). A DFT investigation shows that the increased stability of the [Ln(Me2tedpa)]+ complexes in solution across the lanthanide series is the result of an increased binding energy of the ligand due to the increased charge density of the Ln3+ ion.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk lanthanide complex cross-bridged equilibrium kinetic cyclam
Megjelenés:	Inorganic Chemistry. - 55 : 5 (2016), p. 2227-2239. -
További szerzők:	Regueiro-Figueroa, Martín Esteban-Gómez, David Tripier, Raphaël Tircsó Gyula (1977-) (vegyész, kémia tanár) Kálmán Ferenc K. (1978-) (vegyész) Bényei Attila (1962-) (vegyész) Tóth Imre (1950-) (vegyész) Blas, Andrès de Rodríguez-Blas, Teresa Platas-Iglesias, Carlos
Pályázati támogatás:	OTKA-84291 OTKA OTKA-109029 OTKA COST CM1006 "European F-Element Network (EuFen)" Egyéb COST TD1004 "Theragnostics Imaging and Therapy: An Action to Develop Novel Nanosized Systems for Imaging- Guided Drug Delivery" Egyéb Bolyai János Kutatási Ösztöndíj MTA
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