Relationship between metal-donor distance and ring size in macrocyclic complexes

Martin, Ludmila Y.; DeHayes, Louis J.; Zompa, Leverett J.; Busch, Daryle H.

doi:10.1021/ja00819a071

Cited by 146 publications

(72 citation statements)

References 4 publications

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“…The ZnÀN bond lengths of 2.08 ä and 2.12 ä are comparable with those in reported Zn ± cyclam complexes. [10,11] The average value of the Zn À N bond length (2.10 ä) is very close to the ™ideal∫ metal ± nitrogen bond length (2.07 ä) [18] in trans-cyclam complexes, and close to the ZnÀN bond lengths in complexes containing 1,2-ethanediamine and 1,3-propanediamine. [19] The ZnÀO distance of 2.22 ä for the phthalate complex 2 is slightly longer than that observed for Zn II ± carbonate complexes, [11] and intermediate in value between the ZnÀO bond lengths observed [12] for the chelated acetate in [Zn II (xylylbicyclam)(OAc) 2 ](OAc) 2 (2.09 and 2.41 ä).…”

mentioning

confidence: 63%

Selective Recognition of Configurational Substates of Zinc Cyclam by Carboxylates: Implications for the Design and Mechanism of Action of Anti‐HIV Agents

Liang

Weishäupl

Parkinson

et al. 2003

Chemistry A European J

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The interaction of metal cyclams with carboxylate groups is thought to play an important role in their binding to the CXCR4 chemokine receptor and in their anti-HIV activity. Here we report the synthesis of acetate, phthalate, perchlorate and chloride complexes of Zn(II) cyclam (1,4,8,11-tetraazacyclotetradecane). The X-ray crystal structures of [Zn(cyclam)(phthalate)](n)(CH(3)OH)(2n) and [Zn(cyclam)(H(2)O)(2)](OAc)(2) contain octahedral Zn(II) centres. Phthalate acts as a bridging ligand in the former complex, binding through monodentate carboxylate groups, and giving rise to infinite chains in the lattice together with extensive hydrogen bonding between carboxylate donor oxygen atoms and amine and methanol acceptor atoms. The uncoordinated acetate groups and the aqua ligand in the acetate complex are also involved in a rich network of hydrogen bonds and this may account for the unusually long Zn[bond]O distance (2.27 A). In both crystalline complexes, the macrocycle adopts the trans-III (S,S,R,R) configuration. 1D (1)H NMR spectra of all four complexes have been fully assigned by a combination of 2D [(1)H, (1)H] COSY and TOCSY, and [(1)H, (13)C] and [(1 )H, (15)N] HSQC NMR data. In aqueous solution, the stable trans-III configuration found in the solid-state equilibrates slowly (hours at 298 K) with trans-I (R,S,R,S) and cis-V (R,R,R,R) configurations. The trans-III configuration is predominant in aqueous solution for both the chloride and perchlorate complexes, but for the acetate and phthalate complexes, the cis-V configuration dominates. Carboxylate groups appear to stabilize the cis-V configuration in solution through Zn(II) coordination and hydrogen bonding. Titration of the chloride Zn(II)-cyclam complex with acetate confirmed that carboxylates strongly induce formation of the cis-V configuration. This implies that carboxylates can exert a strong influence over configurational selectivity. Cyclam NH hydrogen bonding is prevalent both in the solid state and in solution, and is relevant to the anti-HIV activity of Zn(II) and other metal cyclam complexes and to their ability to recognize the CXCR4 transmembrane co-receptor.

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mentioning

confidence: 63%

Selective Recognition of Configurational Substates of Zinc Cyclam by Carboxylates: Implications for the Design and Mechanism of Action of Anti‐HIV Agents

Liang

Weishäupl

Parkinson

et al. 2003

Chemistry A European J

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“…In the cyclam-Ni complex, the four imine groups are not equivalent and this seems to be connected with the nickel electronic configuration. Indeed, former experimental reports on the cyclamNi complexes state on the less constrained geometries, when planar configurations hold and stabilize low-spin for Nickel ions [50,51]. However, high-spin state is compatible with a geometry configuration as trans-octahedral complex [52,53].…”

Section: Geometry Of the Cyclam-metal Complexesmentioning

confidence: 99%

Mesoporous Silica Functionalized by Cyclam–Metal Groups: Spectroscopic Studies and Numerical Modeling

Makowska‐Janusik

Kassiba

Errien

et al. 2010

J Inorg Organomet Polym

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Mesoporous silica functionalized by cyclammetal molecules were investigated by spectroscopic methods including Raman, IR, UV-VIS absorption and EPR technique. To analyse quantitatively the physical features, numerical models were developed using the density functional theory method. Thus, the construction of molecular geometries and their optimisation analysis were achieved on the cyclam-metal molecules in vacuum as well as constrained by the host mesoporous silica matrixes. In this context and with regard to the paramagnetic nature of the metals chelated by cyclam molecules, EPR technique allows probing the metal environments which can be compared to theoretical results inferred from numerical models. The vibrational and optical properties were exhaustively investigated and the assignment of the main features was quantitatively discussed thanks to the carried out numerical analyses. The developed approach point out the possibility to define a targeted application of such functional materials based on the possibility to fine tune the absorption features in a wide wavelength range by stabilizing defined configurations of the cyclam-metal groups.

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“…Those with ioslated octahedra seem to have slightly, but possibly significantly, longer distances than those where X-is shared between adjacent octahedra. The 'best-fit' distance is calculated as 2.07/~ by Martin, De Hayes, Zompa & Busch (1974) and a value of 2.05 A is obtained from molecular-mechanics calculations (Th6m, Fox, Boeyens & Hancock, 1984).…”

Section: * Equivalent Positions Formentioning

confidence: 99%

The structure of Ni(cyclam)(ClO4)2

Prasad¹,

Nyburg²,

McAuley³

1987

Acta Crystallogr C

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Relationship between metal-donor distance and ring size in macrocyclic complexes

Cited by 146 publications

References 4 publications

Selective Recognition of Configurational Substates of Zinc Cyclam by Carboxylates: Implications for the Design and Mechanism of Action of Anti‐HIV Agents

Selective Recognition of Configurational Substates of Zinc Cyclam by Carboxylates: Implications for the Design and Mechanism of Action of Anti‐HIV Agents

Mesoporous Silica Functionalized by Cyclam–Metal Groups: Spectroscopic Studies and Numerical Modeling

The structure of Ni(cyclam)(ClO4)2

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