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001-es BibID:	BIBFORM076231
Első szerző:	Molnár Enikő (vegyész)
Cím:	Remarkable differences and similarities between the isomeric Mn(II)-cis- and trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetate complexes / Enikő Molnár, Balázs Váradi, Zoltán Garda, Richárd Botár, Ferenc K. Kálmán, Éva Tóth, Imre Tóth, Ernő Brücher, Gyula Tircsó
Dátum:	2018
ISSN:	0020-1693
Megjegyzések:	Equilibrium, kinetic (solvent exchange and dissociation of the complex) and relaxometric studies (1H and 17O NMR) have been performed with the [M(II)(c-cdta)]2 complexes (c-cdta = cis-1,2-diaminocyclohexane- N,N,N0 ,N0-tetraacetic acid, M(II) = Mn(II), Zn(II), Cu(II),Ca(II), Mg(II)) and the physico-chemical data are compared to the isomeric complexes with trans-1,2-cdta (t-cdta) with the aim of searching appropriate ligands for Mn(II) complexation for safe MRI contrast agents. The total basicity (R log Ki H) of the c-cdta ligand appears to be very similar to that of the trans-derivative under the conditions applied (I = 0.15 M NaCl and 25 C), but the first two protonation constants notably differ. log K1 H is 1.5 log units higher, while the log K2 H is 0.8 log units lower than those determined for the trans-derivative. Similar basicity of the ligands results in similar complex stability (log K[Mn(L)] values are 14.19(2) and 14.32), whereas the conditional stabilities near to physiological pH are different (pMn values are 7.82 and 8.68) for the [Mn (c-cdta)]2 and the [Mn(t-cdta)]2 derivatives, respectively. Dissociation kinetic studies revealed that the [Mn(c-cdta)]2 dissociates 250 times faster than the [Mn(t-cdta)]2 complex. The water exchange rate (kex 298) of [Mn(c-cdta)]2 is ca. 60% higher than that of [Mn(t-cdta)]2 . The differences can likely be attributed to the different distances between the individual donor atoms, and the arrangement of the donor atoms around the metal ions in the cis- and trans- isomers. Interestingly, the relaxivity values of the Mn (II) complexes are very close (r1p = 3.79 mM 1 s 1 and 3.62 mM 1 s 1; 20 MHz, 25 C for the cis- and trans-isomers, respectively). DFT calculations were used to gain insight into the different properties of the [Mn(c-cdta)]2 and the [Mn(t-cdta)]2 complexes. The results gained in our studies confirm that the trans-1,2-cyclohexanediamine ♭♭building block" displays better features for further ligand development.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Inorganica Chimica Acta. - 472 : 1 (2018), p. 254-263. -
További szerzők:	Váradi Balázs (1990-) (vegyész) Garda Zoltán (1989-) (vegyész) Botár Richárd (1992-) (vegyész) Kálmán Ferenc K. (1978-) (vegyész) Tóth Éva Tóth Imre (1950-) (vegyész) Brücher Ernő (1935-) (vegyész) Tircsó Gyula (1977-) (vegyész, kémia tanár)
Pályázati támogatás:	OTKA K-120224 OTKA GINOP-2.3.2-15-2016-00008 GINOP
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM103942
035-os BibID:	(WOS)000528630900017 (Scopus)85080905990
Első szerző:	Tircsó Gyula (vegyész, kémia tanár)
Cím:	Comparison of the equilibrium, kinetic and water exchange properties of some metal ion-DOTA and DOTA-bis(amide) complexes / Gyula Tircsó, Enikő Tircsóné Benyó, Zoltán Garda, Jaspal Singh, Robert Trokowski, Ernő Brücher, A. Dean Sherry, Éva Tóth, Zoltán Kovács
Dátum:	2020
ISSN:	0162-0134 1873-3344
Megjegyzések:	The 1,7-diacetate-4,10-diacetamide substituted 1,4,7,10-tetraazacyclododecane structural unit is common to several responsive Magnetic Resonance Imaging (MRI) contrast agents (CAs). While some of these complexes (agents capable of sensing fluctuations in Zn2+, Ca2+ etc. ions) have already been tested in vivo, the detailed physico-chemical characterization of such ligands have not been fully studied. To fill this gap, we synthesized a representative member of this ligand family possessing two acetate and two n-butylacetamide pendant side-arms (DO2A2M(nBu) = 1,4,7,10-tetraazacyclodoecane-1,7-di(acetic acid)-4,10-di(N-butylacetamide)), and studied its complexation properties with some essential metal and a few lanthanide(III) (Ln(III)) ions. Our studies revealed that the ligand basicity, the stability of metal ion complexes, the trend of stability constants along the Ln(III) series, the formation rates of the Ln(III) complexes and the exchange rate of the bound water molecule in the Gd (III) complex fell between those of Ln(DOTA) - and Ln(DOTA-tetra(amide))(3+) complexes (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, DOTAM = 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane). The only exception is the stability of Cu(DO2A2M(nBu)) which was found to be only slightly lower than that of Cu(DOTA)(2-) (log K-CuL = 19.85 vs. 21.98). This is likely reflects exclusive coordination of the negatively charged acetate donor atoms to the Cu2+ ion forming an octahedral complex with the amides remaining uncoordinated. The only anomaly observed during the study was the rates of acid assisted dissociation of the Ln(III) complexes, which occur at a rate similar to those observed for the Ln(DOTA)(-) complexes. These data indicate that even though the Ln(DO2A2M(nBu))(+) complexes have lower thermodynamic stabilities, their kinetic inertness should be sufficient for in vivo use.
Tárgyszavak:	Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény hazai lapban folyóiratcikk Coordination chemistry Complexes Physico-chemical parameters Synthesis Stability Inertness Water exchange rate
Megjelenés:	Journal of Inorganic Biochemistry. - 206 (2020), p. 1-12. -
További szerzők:	Tircsóné Benyó Enikő (1977-) (vegyész, kémia tanár) Garda Zoltán (1989-) (vegyész) Singh, Jaspal Trokowski, Robert Brücher Ernő (1935-) (vegyész) Sherry, A. Dean Tóth Éva Kovács Zoltán
Pályázati támogatás:	NKFIH-K-120224 Egyéb NKFIH-128201 Egyéb GINOP-2.3.2-15-2016-00008 GINOP
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