Synthesis and guest exchange reactions of inclusion compounds of cucurbit[8]uril with nickel(II) and copper(II) complexes

Mitkina, T. V.; Naumov, Dmitry Yu.; Куратьева, Н. В.; Gerasko, О. А.; Fedin, Vladimir P.

doi:10.1007/s11172-006-0211-5

Cited by 13 publications

(14 citation statements)

References 24 publications

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“…The C···C distances between opposite CH groups in CB8 vary between 12.5 and 13.7 and the distortion parameter of CB8, D(CH) = 1.20 , well falls within the range of 0.2-2.9 found for all CB8 host-guest complexes. [20] As shown in Figure 1, a large part of 1 is not included in the CB8 cavity. Only the tetramethylimidazolidine fragment is rather deeply immersed in the hydrophobic part of the host, and inclusion of the aromatic fragment is not observed.…”

Section: Resultsmentioning

confidence: 99%

Inclusion of a Nitronyl Nitroxyl Radical and Its Hydrochloride in Cucurbit[8]uril

Peresypkina

Fedin

Maurel

et al. 2010

Chemistry A European J

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The recognition properties of cucurbit[8]uril (CB8) toward nitronyl nitroxide 2-(2-benzimidazolyl)-4,4,5,5-tetramethylimidazolidinyl-3-oxide-1-oxy (1) and its hydrochloride have been investigated. 1·HCl led to 1:1 inclusion complex [1·HCl@CB8], which was characterized both in solution and by single-crystal X-ray diffraction. In this compound only the tetramethylimidazolidinyl fragment is included in the host. The magnetic behavior of the complex corresponds to a Curie law with a large separation of the spin carriers in the solid. In contrast, an insoluble species exhibiting ferromagnetic behavior is formed when pure 1 reacts with acid-free CB8. The formula [(1)(2)@(CB8)(3)], in which two radical guests are arranged in such a way that the phenyl groups of the benzimidazolyl substituents are both stacked into one CB8 and the tetramethyl fragments are each capped by a terminal macrocycle, is proposed, in agreement with microanalysis, spectrophotometric, EPR, and magnetic measurements. According to McConnell's rules, the alternating spin densities within the stacked aromatic fragments result in a ferromagnetic interaction (J=+2.3 cm(-1), H=-2JS(1)S(2)) and a triplet ground spin state for the inclusion complex.

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Section: Resultsmentioning

confidence: 99%

Inclusion of a Nitronyl Nitroxyl Radical and Its Hydrochloride in Cucurbit[8]uril

Peresypkina

Fedin

Maurel

et al. 2010

Chemistry A European J

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“…The axial chloride ligands in 1A and 1B are embedded in the cavity of CB [8]. This arrangement of the complexes with chloride ligands differs from the orientation of the aqua complexes in the cavity of CB [8], in which the trans positions in the coordination environment of the metal atoms are occupied by water molecules, {trans [Cu(en) 2 22 The aqua complexes are arranged so that the MN 4 plane almost coincides with the equatorial plane of CB [8], and the aqua ligands are locat ed at the portals of the cavitand rather than inside the cavity. The fact that the aqua and chloro complexes as the guests are in different orientations in the cavities of CB [8] Scheme 1 is apparently attributed to the difference in the nature of the axial ligands.…”

Section: Resultsmentioning

confidence: 99%

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

et al. 2010

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Inclusion compounds of the macrocyclic cavitand cucurbit[8]uril (CB[8]) with the ruthenium(III) bis(ethylenediamine) complex {trans [Ru(en) 2 Cl 2 ]@CB[8]}Cl•27.5H 2 O (1), the gold(III) diethylenetriamine complex {[Au(dien)Cl]@CB[8]}Cl 2 •11H 2 O (2), and the gold(III) and platinum(II) cyclam complexes (H 3 O) 5 {[Au(cyclam)]@CB[8]}Cl 8 •18H 2 O (3) and {[Pt(cyclam)] 0.11 (H 2 cyclam) 0.89 @CB[8]}Cl 2 •16H 2 O (4), respectively, where cyclam is the tetra azamacrocyclic ligand, were synthesized. The inclusion compounds were synthesized both directly starting from CB[8] and the metal complexes with polyamines (en or dien) and by the two step method with the use of the cyclic polyamine ligand (cyclam) pre included into the cavity of the macrocycle. The inclusion compounds were characterized by X ray diffraction (1, 2, and 4), IR spectroscopy, electrospray ionization mass spectrometry, UV-Vis spectro scopy, and thermogravimetric analysis.Cucurbit[n]urils (C 6n H 6n N 4n O 2n , CB[n]; n = 5-10) comprise a family of macrocyclic molecules containing an open hydrophobic intramolecular cavity accessible through two hydrophilic portals formed by n carbonyl groups. 1-4 This structure determines the behavior of cucurbit[n]urils as cavitands, viz., host molecules capable of encapsulating guest molecules of suitable size into the inner cavity. A high negative electrostatic potential on the portals 3 is responsible for the formation of stable inclusion compounds of CB[n] with positively charged guests, for example, with alkylammonium cations. 2,3 The cavity sizes in cucurbit[n]urils with n > 6 are sufficient for the inclu sion of metal complexes with small organic ligands. The spectroscopic (NMR), calorimetric, and electrochemical studies showed that highly stable host-guest compounds are formed. 5-9 However, only a few inclusion com pounds of CB[n] with metal complexes were structurally characterized. 6,10-12 Complexes included into the bar rel shaped cavity of CB[n] can be fully embedded in the cavitand, as opposed to most of inclusion compounds of such receptors as calixarenes and cyclodextrins where com plexes are only partially encapsulated in the bowl shaped cavities. 13 In recent years, this class of compounds has attracted considerable interest because of the possibility of the inclusion of biologically active metal complexes into cavitands. This opens wide opportunities for the design of new generation prolonged action pharmaceuticals in which the host molecules prevents the guest molecules from rapid decomposition, decrease their toxicity, and have the transport function of the active component in the organism. 14 Recent studies 14-16 have shown that the in clusion of platinum polyamine complexes having antitu mor activity into cucurbit[n]urils leads to a substantial decrease in the toxicity of these complexes. Antitumor drugs containing inclusion compounds of CB[7] and CB [8] with platinum, palladium, and gold complexes were cov ered by patents. 17-20Previously, 21-25 we have shown that CB[8] forms inclusion compoun...

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“…It is known that among CB[ n ] homologues the cavitand CB[7] is well‐soluble in water and as such it has been well studied. However, CB[8] and its higher homologues that have larger cavities are more often used in the synthesis of inclusion compounds with metal complexes, especially with polydentate ligands . It is for this reason that we chose CB[8] as one of the objects of this study.…”

Section: Introductionmentioning

confidence: 99%

Formation of aqua and tetraammine Cu(II) complexes inside the cavities of cucurbit[6,8]urils: A DFT forecast

Masliy

Grishaeva

Kuznetsov

2018

Int J of Quantum Chemistry

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Results of DFT calculations of the structure and thermodynamics of formation of aqua and tetraammine Cu(II) complexes inside CB[n] (n = 6,8) are presented in this study. Formation thermodynamics of the complexes in the cavitands was evaluated by taking into account the most probable number of water molecules inside CB[n]. In this methodology, the complexation was first considered as a substitution reaction in which the guest complex displaces partially or completely the water molecules that are located inside the cavity. The water molecules present in the cavitand were shown to play an important role in the fixation of the guest complex inside the cavity due to the hydrogen bonds with the oxygen portals. The hydration of Cu(II) ion inside CB[6] leads to the formation of an inclusion compound with the formula {[Cu(H2O)4]2+·2H2O}@CB[6] while in CB[8] {[Cu(H2O)6]2+·4H2O}@CB[8] is formed. For the binding of tetraammine Cu(II) complex, CB[8] was determined to be a significantly more suitable “container” than CB[6]. Both a direct embedding of this complex into the CB[8] and another mechanism in which ammonia molecules replace the water molecules in the Cu(II) aqua complex, preexisting in CB[8] were determined to be thermodynamically possible. Both these lead to the formation of the resultant inclusion compound described by the formula {[Cu(NH3)4(H2O)2]2+·4H2O}@CB[8].

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Synthesis and guest exchange reactions of inclusion compounds of cucurbit[8]uril with nickel(II) and copper(II) complexes

Cited by 13 publications

References 24 publications

Inclusion of a Nitronyl Nitroxyl Radical and Its Hydrochloride in Cucurbit[8]uril

Inclusion of a Nitronyl Nitroxyl Radical and Its Hydrochloride in Cucurbit[8]uril

Inclusion compounds of cucurbit[8]uril with noble metal polyamine complexes

Formation of aqua and tetraammine Cu(II) complexes inside the cavities of cucurbit[6,8]urils: A DFT forecast

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