Structure and exchange behavior of cryptand 111 and its inside protonated products

Bruegge, H. J.; Carboo, D.; Deuten, K. Von; Knoechel, A.; Kopf, Jürgen; Dreissig, W.

doi:10.1021/ja00261a018

Cited by 41 publications

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“…The readily available information on crypt‐111 protonation in solution contrasts with the poor information available on the structural and dynamic aspects of protonated crypt‐111 in the solid state. No atomic coordinates are available in the Cambridge Structural Database (CSD, ConQuest 1.19 version) for H + ⊂crypt‐111 species, with only selected data for H + ⊂crypt‐111 picrate being reported . The proton location and motion in other proton sponges, for example, 1,8‐dimethylaminonaphtalene and its analogues, have been extensively studied, but the same features have never been investigated for H + ⊂crypt‐111 in the solid state.…”

Section: Methodsmentioning

confidence: 99%

“…No atomicc oordinates are available in the Cambridge StructuralD atabase( CSD, ConQuest 1.19 version) for H + &crypt-111 species, [21] with only selected data for H + &crypt-111 picrate being reported. [22] The protonl ocation and motion in other protonsponges, for example, 1,8-dimethylaminonaphtalene [23] and its analogues, [24] have been extensively studied,b ut the same features have never been investigated for H + &crypt-111 in the solid state. Hereinw ed escribe some experimentalo bservations and theoretical calculations on the H + &crypt-111 cation.…”

mentioning

confidence: 99%

“…The crystal shows high symmetry that is related to the mirrorp lane through the three oxygen atoms of crypt-111.T he cation adopts an in-in + conformation ( Figure 1) with ar ugby-balls hape (intramolecular NÀNa nd OÀOs eparations are 369.6 and 364.7 pm, Ta ble S.4 in the Supporting Information). In-out + and out-out + conformationsh ave been observed in solution, [17] but the in-in arrangement is the most stable for the free cryptand and the protonated derivatives in the gas, [18] liquid, [17] and solid [22] phases.T he nitrogen atoms adopt ad istorted tetrahedral conformation (]CÀNÀC = 112.908).…”

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confidence: 99%

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Proton in a Confined Space: Structural Studies of H⁺⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Kumar

Pilati

Quici

et al. 2017

Chemistry A European J

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Experimental observations and modeling data are reported on the solid-state structural features of crypt- 111⋅HI (1) and the three-component co-crystals that 1 forms with α,ω-diiodoperfluoroalkanes 2 a-d. X-ray analyses indicate that, in all five systems and at low temperature, the caged proton is covalently bonded to a single nitrogen atom and is involved in a network of intramolecular hydrogen bonds. In contrast, room-temperature, solid-state N NMR spectroscopy suggests magnetic equivalency of the two N atoms of crypt-111 in both 1 and co-crystals of 1 with diiodoperfluoroalkanes. Computational modelling confirms that the acidic hydrogen inside the cavity preferentially sits along the internitrogen axis and is covalently bonded to one nitrogen. The computed energy barriers suggest that the hopping of the encapsulated proton between the two N atoms of the cage can occur in the halogen-bonded co-crystals of 1⋅2, but it is hardly possible in the pure H ⊂crypt-111 iodide 1. These different pictures of the proton position and dynamics obtained by using different techniques and conditions confirm the unique characteristics of the confined space within the cavity of crypr-111 and the distinctive features of processes occurring therein.

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Section: Methodsmentioning

confidence: 99%

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Proton in a Confined Space: Structural Studies of H⁺⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Kumar

Pilati

Quici

et al. 2017

Chemistry A European J

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“…[1,2] The presence of basic amino sites in the macrocyclic molecule also enables diffusion of a proton inside the molecular cavity, followed by ligand protonation and formation of the protonated derivatives. [3] In general, the proton transfer reaction is of great importance in chemistry and biology. It plays a fundamental role in numerous processes including acid-base neutralization and electrophilic addition, and it is involved in transport phenomena, photosynthesis, enzyme reactions, and the like.…”

Section: Introductionmentioning

confidence: 99%

Influence of the hydrogen bonding on the basicity of selected macrocyclic amines

Nasiri

Shakourian‐Fard

Fattahi

2012

J of Physical Organic Chem

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The optimized minimum-energy geometries of different macrocyclic amines and their protonated structures were determined by using ab initio and density functional theory (DFT) calculations. All the gas phase optimizations and energy calculations were performed at the DFT/B3LYP/6-311++G(d,p) level of theory. The HF/6-31 + G(d,p) level was used for all single point calculations in the solution phase. Geometry optimizations indicate that the most stable structures are stabilized by intramolecular hydrogen bonds. The proton affinity (PA) of macrocyclic amines is controlled by the strength of intramolecular hydrogen bonds of macrocyclic amines. These hydrogen bonds strongly influence the basicity of heteroatoms in macrocycles. The highest PA value among the studied macrocyclic amines was found to be 264.9 kcal mol À1 for structure 7. This is comparable with PA of proton sponges such as 1,8-bis(dimethylamino)naphthalene. The solution phase calculations were carried out in the dimethyl sulfoxide solution as a commonly used solvent in organic reactions. Natural bond orbital analysis was performed to calculate the charge transfers and the second-order interaction energies (E (2) ) between the donor and acceptor. Quantum theory of atoms in molecules (QTAIM) was also applied to determine the nature of hydrogen bonds. QTAIM studies showed that the intramolecular hydrogen bonds in these structures are electrostatic (closed-shell) interactions as well as partially covalent and partially electrostatic in nature.

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“…In this paper we present fully optimized structures of [ 11 11-cryptand 11-cryptate (hereaftercalled c l l l , H+cl11, Li+clll, H$+c111, H c l l l , and Hzclll) under the constraints imposed by the D3h, C3h, Ds, (23, cz, or c, point group. Note: the term "cryptate" may not be the most appropriate Structure correlation diagram.…”

Section: Introductionmentioning

confidence: 99%

An ab Initio Investigation of [111]-Cryptates: Their Structure and Their Chemistry

Boehm¹,

Rencsok²,

Harrison³

et al. 1994

J. Phys. Chem.

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We have modeled at the HF/6-31G (and 6-31G+) level. Ground-state equilibrium geometries of H+cl 1 1 and H c l 1 1 belong to the C3 point group, while the cryptand itself may belong to either C3 or C3h. Inspection of all equilibrium structures indicated no significant geometric difference between the respective charged and neutral species, although complexation (whether charged or not) leads to significant changes in the N--N and 0-0 distances. Factors affecting proton hopping between nitrogens are discussed, including barrier height, tunneling, and a possible coupling between the electronic degrees of freedom and migration of the encapsulated proton. We argue that none of these effects are important. Instead, solvent effects probably dominate this process. We have found a barrier height of 17 kcal/mol for internal exchange of the internal proton (or hydrogen), where each saddle point corresponds to a stationary point in C, space within the Hartree-Fock description. The related isomerization (C3 to C3) involving the uncomplexed cryptand is nearly barrier free. The lowest energy isomer of the H c l 1 1 is clearly Rydberg-like (with a complexed proton), while the lowest energy isomer of Hzcl 1 1 has a more common valence-like electron distribution.

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Structure and exchange behavior of cryptand 111 and its inside protonated products

Cited by 41 publications

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Proton in a Confined Space: Structural Studies of H⁺⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Proton in a Confined Space: Structural Studies of H⁺⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Influence of the hydrogen bonding on the basicity of selected macrocyclic amines

An ab Initio Investigation of [111]-Cryptates: Their Structure and Their Chemistry

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Structure and exchange behavior of cryptand 111 and its inside protonated products

Cited by 41 publications

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Proton in a Confined Space: Structural Studies of H+⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Proton in a Confined Space: Structural Studies of H+⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Influence of the hydrogen bonding on the basicity of selected macrocyclic amines

An ab Initio Investigation of [111]-Cryptates: Their Structure and Their Chemistry

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Proton in a Confined Space: Structural Studies of H⁺⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives

Proton in a Confined Space: Structural Studies of H⁺⊂Crypt‐111 Iodide and Some Halogen‐Bonded Derivatives