Tris(triazolyl)borate ligands of intermediate steric bulk for the synthesis of biomimetic structures with hydrogen bonding and solubility in hydrophilic solvents

Gardner, Sean; Papish, Elizabeth T.; Monillas, Wesley H.; Yap, Glenn P. A.

doi:10.1016/j.jinorgbio.2008.08.010

Cited by 16 publications

(18 citation statements)

References 39 publications

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“…It must be remembered that the usual coordination of Na + is 6 (very seldom 8) (Mä hler & Persson, 2011;Maria et al, 2009). The average Na-N bond length of 2.62 (2) Å is comparable with those reported previously for tris(pyrazolyl)borate Na complexes (Chisholm et al, 2006;Dias & Goh, 2004;Hu et al, 2009;Gardner et al, 2008;King et al, 2009;Reglinski et al, 1999) and tris(pyrazolyl)methane Na complexes (Reger et al 2001(Reger et al , 2002Maria et al, 2009). The H atoms of the carboxylic acid groups were assigned to each O atom having a longer C-O bond as free acids, except for O4, which is bound to Na as part of the carboxylate anion.…”

Section: Resultssupporting

confidence: 86%

A tris(pyrazol-1-yl)methane bearing carboxylic acid groups at position 4: {1-[bis(4-carboxy-3,5-dimethyl-1H-pyrazol-1-yl)methyl]-3,5-dimethyl-1H-pyrazole-4-carboxylato}sodium dihydrate

Alkorta

Elguero²,

García³

et al. 2013

Acta Crystallogr C

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Section: Resultssupporting

confidence: 86%

A tris(pyrazol-1-yl)methane bearing carboxylic acid groups at position 4: {1-[bis(4-carboxy-3,5-dimethyl-1H-pyrazol-1-yl)methyl]-3,5-dimethyl-1H-pyrazole-4-carboxylato}sodium dihydrate

Alkorta

Elguero²,

García³

et al. 2013

Acta Crystallogr C

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“…References are in this work (Ttz i Pr2 ), Gardner et al (Ttz Ph,Me ), and Bongiovanni et al (Ttz t Bu,Me ) …”

Section: Discussionmentioning

confidence: 61%

“…We postulated that any enzyme that uses water in its reaction chemistry (such as CA) could be better modeled by incorporating ligands that promote water‐solubility. Tris(triazolyl)borate (Ttz) complexes have improved water‐solubility, relative to the more commonly used (in enzyme modeling) tris(pyrazolyl)borate (Tp) complexes (Scheme , b and c) , . Ttz ligands typically bind to a metal center via endodentate binding (shown in red, Scheme , b).…”

Section: Introductionmentioning

confidence: 99%

“…Despite these goals, the synthesis of (Ttz)Zn(OH) complexes for CO 2 activation has been challenging and this target has been elusive until recently , . We have used three different Ttz ligands of varying relative steric profile: Ttz Ph,Me (small),, Ttz i Pr2 (medium), and Ttz t Bu,Me (large) (wherein the superscripts indicate the three and five position substituents on the triazole rings). A numbering scheme for the compounds described herein is presented in Table .…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Biomimetic Zinc Complexes for CO2 Activation and the Influence of Steric Changes in the Ttz Ligands [Ttz = Tris(triazolyl)borate]

et al. 2015

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Carbon dioxide fixation with zinc complexes of the anionic tris(triazolyl)borate (Ttz) ligand offers biomimetic structures in a hydrophilic environment. However, the synthetic result depends greatly on the steric bulk of the Ttz ligand. Synthetic routes adapted from the synthesis of (Tp)ZnOH have been applied to bulky Ttz ligands, but side products often result because Ttz frequently forms complexes with +1 metals or cations used in the synthesis. Nonetheless, (Ttz tBu,Me )-ZnOH (1) has been successfully synthesized and crystallographically characterized, but only via the hydrolysis of the zinc (hex-(1) [a] 2495 Scheme 2. The application of synthetic routes that are known in the literature to form TpZnOH leads to different results when applied to the formation of biomimetic Ttz zinc complexes. However, zinc hydroxide complexes of Ttz can be achieved in some cases. In this Scheme M = Na, K, NMe 4 and L = Tp or Ttz of varied steric bulk (this work focuses on L = Ttz tBu,Me , Ttz iPr2 , Ttz Ph,Me ). 2496Scheme 3. Successful route to (Ttz tBu,Me )ZnOH (1) via Zn amide (6). Zn amide structure is tentatively assigned as κ 3 or κ 2 .Scheme 4. Synthesis of the zinc hydroxide (2a) and zinc carbonate (2b) complexes. Two equivalents of 2a react with CO 2 to eliminate water and form one equivalent of 2b.

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“…Bulky tris(3,5-R,R'-1, 2, 4-triazolyl)borate (Ttz R,R' ) ligands support low coordinate metalcenters that are suitable for catalysis. [8,[29][30][31][32][33][34][35][36][37] Ttz complexes of copper(I) show that electrophilic C-H activation reactions can be enhanced by ligand protonation. [29] Ttz ligands offer facial coordination and ease of steric modification at the metal center similar to the more commonly used tris(3-R-5-R'-1,2-pyrazolyl)hydroborate (Tp R,R' ) ligands ( Figure 2).…”

Section: Introductionmentioning

confidence: 99%

Electrochemical reduction of Ttz copper(II) complexes in the presence and absence of protons: Processes relevant to enzymatic nitrite reduction (TtzR,R′= tris(3-R, 5-R′-1, 2, 4-triazolyl)borate)

Siek

Dixon

Papish

2017

Inorganica Chimica Acta

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Tris(triazolyl)borate (Ttz) is a proton responsive ligand, and the redox potential of Ttz complexes can be altered by protonation. Protonation events can therefore alter the thermodynamics of reduction of copper complexes, and this is relevant to nitrite reduction mediated by copper complexes wherein Cu(II) reduction to Cu(I) is the first step. The electrochemical behavior of tris(triazolyl)borate and the corresponding copper complexes, Ttz tBu,Me CuCl (1) and Ttz tBu,Me CuNO 2 (2), was investigated under both neutral and acidic conditions. Upon protonation, reduction of 1 is shifted more positive (E pc = 290 mV) upon addition of 1.0 equiv. of acid. This result indicates that ligand protonation facilitates the reduction process, which is also evident from the UV-Vis spectral data. In contrast, with the Ttz tBuMe CuNO 2 (2) analogue, the reduction peak shifted towards a more negative potential while UV-Vis spectra shows no significant changes as acid is added. This suggests that the protons may not be involved in assisting the redox process but rather lead to decomposition events at reducing potentials. Other electrochemical control studies on a series of compounds, namely (Ttz tBu,Me)ZnCl (3), (Ttz tBu,Me)K (4), H(Ttz tBu,Me) (5), and Htz tBu,Me (6), were also conducted with and without acid present. These studies have shown that triazole rings, by themselves and in metal complexes, are not redox active under the conditions we have used. We therefore conclude that the Ttz ligand (including in 1 and 2) is not a site for reduction in our studies.

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Tris(triazolyl)borate ligands of intermediate steric bulk for the synthesis of biomimetic structures with hydrogen bonding and solubility in hydrophilic solvents

Cited by 16 publications

References 39 publications

A tris(pyrazol-1-yl)methane bearing carboxylic acid groups at position 4: {1-[bis(4-carboxy-3,5-dimethyl-1H-pyrazol-1-yl)methyl]-3,5-dimethyl-1H-pyrazole-4-carboxylato}sodium dihydrate

A tris(pyrazol-1-yl)methane bearing carboxylic acid groups at position 4: {1-[bis(4-carboxy-3,5-dimethyl-1H-pyrazol-1-yl)methyl]-3,5-dimethyl-1H-pyrazole-4-carboxylato}sodium dihydrate

Synthesis of Biomimetic Zinc Complexes for CO2 Activation and the Influence of Steric Changes in the Ttz Ligands [Ttz = Tris(triazolyl)borate]

Electrochemical reduction of Ttz copper(II) complexes in the presence and absence of protons: Processes relevant to enzymatic nitrite reduction (TtzR,R′= tris(3-R, 5-R′-1, 2, 4-triazolyl)borate)

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