Lanthanide(<scp>III</scp>) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of [La(tcmc)(CF3SO3)(EtOH)](CF3SO3)2

Amin, Shahid; Morrow, Janet R.; Lake, Charles H.; Churchill, Melvyn Rowen

doi:10.1002/anie.199407731

Cited by 176 publications

(106 citation statements)

References 20 publications

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“…[6] Removal of one or two carboxylates from the ligand DOTA results in a decrease in complex stability and an increase in the number of inner-sphere water molecules [see structures of DO3A ϭ 1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane and DO2A ϭ 1,7-bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane in Scheme 1].…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Yerly

Dunand

Tóth

et al. 2000

Eur. J. Inorg. Chem.

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The hydration state of a series of [Ln(DO2A)(H2O)n]+ complexes in aqueous solution at pH = 6.4–7.0 was studied by measuring the lanthanide‐induced 17O shifts (LIS) of water [Ln includes elements from Ce to Yb; DO2A = 1,7‐bis(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane]. Their contact contribution, obtained from Reilley plots, indicated a decrease in the inner‐sphere water coordination number of the [Ln(DO2A)(H2O)n]+ complexes from n = 3 (Ce–Eu), to n = 2 (Tb–Yb). A temperature‐dependent UV/Vis absorption study of the 578–582 nm 7F0 → 5D0 transition band of [Eu(DO2A)(H2O)n]+ in aqueous solution showed that this complex is present in an equilibrium between eight‐ and nine‐coordinate species with n = 2 and n = 3, respectively. The hydration equilibrium parameters (2 ↔ 3), K2–3298= 4.0 ± 0.2, ΔH2–30 = –12.1 ± 1 kJ mol–1 and ΔS 2–30 = –28.9 ± 3 J mol–1 K–1,correspond to an average hydration number of 2.65–2.85 in the temperature range 273–363 K. A variable temperature, multiple field 17O NMR study combined with direct EPR measurements of the transverse electronic relaxation rates has been used to obtain the parameters characterizing water exchange, rotation and electronic relaxation, all influencing the proton relaxivity of [Gd(DO2A)(H2O)2–3]+. The small increase in the water exchange rate of [Gd(DO2A)(H2O)2–3]+ (k ex298 = (10 ± 5) × 106s–1) relative to that of[Gd(DOTA)(H2O)]– (4.8 × 106 s–1) is a consequence of an unfavorable interplay of charge and hydration equilibria. The value of τ R298 = 40 ± 1 ps is short, and the electronic relaxation rate (1/T2e ≈︁ 1.2 × 1010 s–1) is fast relative to [Gd(DOTA)(H2O)]– (1.3–2.4 × 109 s–1 for B = 0.34 T). These parameters negate to some extent the expected increase in proton relaxivity of the [Gd(DO2A)(H2O)2–3]+ complex.

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Section: Introductionmentioning

confidence: 99%

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Yerly

Dunand

Tóth

et al. 2000

Eur. J. Inorg. Chem.

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“…This is in agreement with the findings of Morrow and co-workers, who have shown that increased rate constants can be obtained when two metal bound water molecules are present. 48 The pH-rate profile for the two La(III) 3′pyridine complexes, 3·La(III) and 4·La(III), was similar regardless of the level of substitution (ESI Fig. S5 †); both complexes exhibited a bell shaped curve maximum at around pH 8.4 for hydrolytic activity.…”

Section: Rate Of Hydrolysismentioning

confidence: 92%

“…The HEPES buffer (at 50 mM) was chosen due to its optimal pH range (log K a value of HEPES is 7.55) while the high concentration was found to reduce pH drift of ± 0.2 pH units. 48 The most efficient complexes at promoting hydrolysis of HPNP were 4·Eu(III) and 4· La(III), the pH rate profile of both is shown in Fig. 3.…”

Section: Rate Of Hydrolysismentioning

confidence: 95%

Tri- and tetra-substituted cyclen based lanthanide(iii) ion complexes as ribonuclease mimics: a study into the effect of log K_a, hydration and hydrophobicity on phosphodiester hydrolysis of the RNA-model 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP)

2015

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A series of tetra-substituted 'pseudo' dipeptide ligands of cyclen (1,4,7,10,-tetraazacyclododecane) and a tri-substituted 3'-pyridine ligand of cyclen, and the corresponding lanthanide(III) complexes were synthesised and characterised as metallo-ribonuclease mimics. All complexes were shown to promote hydrolysis of the phosphodiester bond of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP, τ 1/2 = 5.87 × 10 3 h), a well known RNA mimic. The La(III) and Eu(III) tri-substituted 3'-pyridine lanthanide(III) complexes being the most efficient in promoting such hydrolysis at pH 7.4 and at 37°C; with τ 1/2 = 1.67 h for La(III) and 1.74 h for Eu(III). The series was developed to provide the opportunity to investigate the consequences of altering the lanthanide(III) ion, coordination ability and hydrophobicity of a metallo-cavity on the rate of hydrolysis using the model phosphodiester, HPNP, at 37°C. To further provide information on the role that the log K a of the metal bound water plays in phosphodiester hydrolysis the protonation constants and the metal ion stability constants of both a tri and tetra-substituted 3'pyridine complex were determined.Our results highlighted several key features for the design of lanthanide(III) ribonucelase mimics; the presence of two metal bound water molecules are vital for pH dependent rate constants for Eu(III) complexes, optimal pH activity approximating physiological pH (∼7.4) may be achieved if the log K a values for both MLOH and ML(OH) 2 species occur in this region, small changes to hydrophobicity within the metallo cavity influence the rate of hydrolysis greatly and an amide adjacent to the metal ion capable of forming hydrogen bonds with the substrate is required for achieving fast hydrolysis.

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“…Instead, suitable ligands are designed and used to form trivalent lanthanide complexes to control lanthanide-promoted hydrolysis for more specific usage. [5][6][7][8][9][10][11][12][13][14] We have been interested in the use of macrocyclic lanthanide complexes as artificial nucleases and ribonucleases, because these complexes are thermodynamically more stable and kinetically inert. Previously we reported the coordina-…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Bis(p‐nitrophenyl)phosphate (BNPP) Hydrolysis Reactions with Trivalent Lanthanide Complexes of N‐Hydroxyethyl(ethylenediamine)‐ N,N′,N′‐triacetate (HEDTA)

2009

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Lanthanide(III) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of [La(tcmc)(CF₃SO₃)(EtOH)](CF₃SO₃)₂

Cited by 176 publications

References 20 publications

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Tri- and tetra-substituted cyclen based lanthanide(iii) ion complexes as ribonuclease mimics: a study into the effect of log K_a, hydration and hydrophobicity on phosphodiester hydrolysis of the RNA-model 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP)

Kinetics of Bis(p‐nitrophenyl)phosphate (BNPP) Hydrolysis Reactions with Trivalent Lanthanide Complexes of N‐Hydroxyethyl(ethylenediamine)‐ N,N′,N′‐triacetate (HEDTA)

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Lanthanide(III) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of [La(tcmc)(CF3SO3)(EtOH)](CF3SO3)2

Cited by 176 publications

References 20 publications

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Spectroscopic Study of the Hydration Equilibria and Water Exchange Dynamics of Lanthanide(III) Complexes of 1,7-Bis(carboxymethyl)-1,4,7,10-tetraazacyclododecane (DO2A)

Tri- and tetra-substituted cyclen based lanthanide(iii) ion complexes as ribonuclease mimics: a study into the effect of log Ka, hydration and hydrophobicity on phosphodiester hydrolysis of the RNA-model 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP)

Kinetics of Bis(p‐nitrophenyl)phosphate (BNPP) Hydrolysis Reactions with Trivalent Lanthanide Complexes of N‐Hydroxyethyl(ethylenediamine)‐ N,N′,N′‐triacetate (HEDTA)

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Product

Resources

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Lanthanide(III) Tetraamide Macrocyclic Complexes as Synthetic Ribonucleases: Structure and Catalytic Properties of [La(tcmc)(CF₃SO₃)(EtOH)](CF₃SO₃)₂

Tri- and tetra-substituted cyclen based lanthanide(iii) ion complexes as ribonuclease mimics: a study into the effect of log K_a, hydration and hydrophobicity on phosphodiester hydrolysis of the RNA-model 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP)