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Journal ArticleDOI

Chiral resolution of l- and d-alanine and a racemic macrocyclic nickel(II) complex: synthesis and crystal structures

01 Mar 2014-Transition Metal Chemistry (Springer International Publishing)-Vol. 39, Iss: 2, pp 135-140
TL;DR: In this paper, the reaction of a racemic four-coordinate Ni(II) complex [Ni(rac-L)](ClO4)2 with l- and d-alanine in acetonitrile/water gave two sixcoordinate enantiomers formulated as Ni(RR-L)(l-Ala) and ClO4·2CH3CN, respectively.
Abstract: The reactions of a racemic four-coordinate Ni(II) complex [Ni(rac-L)](ClO4)2 with l- and d-alanine in acetonitrile/water gave two six-coordinate enantiomers formulated as [Ni(RR-L)(l-Ala)](ClO4)·2CH3CN (1) and [Ni(SS-L)(d-Ala)](ClO4) (2) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclo-tetradecane, Ala− = alanine anion), respectively. Evaporation from the remaining solutions gave two four-coordinate enantiomers characterized as [Ni(SS-L)](ClO4)2 (S-3) and [Ni(RR-L)](ClO4)2 (R-3), respectively. Single-crystal X-ray diffraction analyses of complexes 1 and 2 revealed that the Ni(II) atom has a distorted octahedral coordination geometry, being coordinated by four nitrogen atoms of L in a folded configuration, plus one carboxylate oxygen atom and one nitrogen atom of l- or d-Ala− in mutually cis-positions. Complexes 1 and 2 are supramolecular stereoisomers, constructed via hydrogen bonding between [Ni(RR-L)(l-Ala)]+ or [Ni(SS-L)(d-Ala)]+ monomers to form 1D hydrogen-bonded zigzag chains. The homochiral natures of complexes 1 and 2 have been confirmed by CD spectroscopy.
Citations
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01 Jan 2017
TL;DR: In this article, 3D fragment descriptors have been applied to discriminate between stereoisomers in predictive QSPR modeling of the standard free energy (∆G°) for the 1:1 inclusion complexation of 76 chiral guests with β-cyclodextrin (β-CD) and 40 chiral neighbors with 6-amino-6-deoxy-β-cyclodesyntextrin (am-β -CD) in water at 298 K.
Abstract: We report new 3D fragment descriptors to model parameters and properties of stereoisomeric molecules and conformers. New 3D fragment descriptors have been applied to discriminate between stereoisomers in predictive QSPR modeling of the standard free energy (∆G°) for the 1:1 inclusion complexation of 76 chiral guests with β-cyclodextrin (β-CD) and 40 chiral guests with 6-amino-6-deoxy-β-cyclodextrin (am-β-CD) in water at 298 K. The in-house software, mfSpace (Molecular Fragments Space), was used for QSPR modeling, generation and coding of the 3D fragment descriptors. The program implements the Singular Value Decomposition for Multiple Linear Regression analysis as machine learning method. We used ensemble modeling techniques which include the generation of many individual models, the selection of the most relevant ones and followed by their joint application to test compounds, i.e., applying a consensus model for average predictions. The models based on 2D and 3D fragment descriptors provide the best predictions in external fivefold cross-validation: root mean squared error RMSE = 1.1 kJ/mol and determination coefficient $$R_{{det}}^{2}$$Rdet2 = 0.918 (β-CD), RMSE = 0.89 kJ/mol and $$R_{{det}}^{2}$$Rdet2 = 0.910 (am-β-CD).

5 citations


Cites background from "Chiral resolution of l- and d-alani..."

  • ...l-alanine [55] has the fragment C–C–C=O_abC, when d-alanine [55] possesses the fragment C–C–C=O_abA, and cis- and trans-β-butylene have the fragments C–C=C–C_bbA and C–C=C–C_bbD, respectively....

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Journal ArticleDOI
TL;DR: In this paper, 3D fragment descriptors have been applied to discriminate between stereoisomers in predictive QSPR modeling of the standard free energy (∆G°) for the 1:1 inclusion complexation of 76 chiral guests with β-cyclodextrin (β-CD) and 40 chiral neighbors with 6-amino-6-deoxy-β-cyclodesyntextrin (am-β -CD) in water at 298 K. The program implements the Singular Value Decomposition for Multiple Linear Regression analysis as machine learning method
Abstract: We report new 3D fragment descriptors to model parameters and properties of stereoisomeric molecules and conformers. New 3D fragment descriptors have been applied to discriminate between stereoisomers in predictive QSPR modeling of the standard free energy (∆G°) for the 1:1 inclusion complexation of 76 chiral guests with β-cyclodextrin (β-CD) and 40 chiral guests with 6-amino-6-deoxy-β-cyclodextrin (am-β-CD) in water at 298 K. The in-house software, mfSpace (Molecular Fragments Space), was used for QSPR modeling, generation and coding of the 3D fragment descriptors. The program implements the Singular Value Decomposition for Multiple Linear Regression analysis as machine learning method. We used ensemble modeling techniques which include the generation of many individual models, the selection of the most relevant ones and followed by their joint application to test compounds, i.e., applying a consensus model for average predictions. The models based on 2D and 3D fragment descriptors provide the best predictions in external fivefold cross-validation: root mean squared error RMSE = 1.1 kJ/mol and determination coefficient $$R_{{det}}^{2}$$ = 0.918 (β-CD), RMSE = 0.89 kJ/mol and $$R_{{det}}^{2}$$ = 0.910 (am-β-CD).

4 citations

Journal ArticleDOI
TL;DR: In this paper, three enantiomeric pairs of novel homochiral coordination compounds (HCCs) with the formula {[Zn(D-hpg)(4,4′-bipy)(H2O)] · (NO3)}n 1-L, {Zn (Lhpg)2(4, 4′-Bipy)

2 citations

Journal ArticleDOI
TL;DR: In this article, the macrocyclic nickel(II) complexes can easily take up and fix atmospheric CO2 at room temperature, and the chiral nature of complex 2 has been confirmed by CD spectroscopy.
Abstract: Two dinuclear carbonato-bridged nickel(II) complexes formulated as [Ni(rac-L)]2(µ-CO3)(H2O)(im)4(ClO4)2 (1) and [Ni(SS-L)]2(µ-CO3)(H2O)(im)4(ClO4)2 (2) (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane, im = imidazole) were isolated from the reactions of [Ni(rac-L)](ClO4)2 and [Ni(SS-L)](ClO4)2 with imidazole in the air, respectively, and a hydrocarbonato-coordinated nickel(II) complex formulated as [Ni(rac-L)](HCO3)(ClO4) (3) was reacted with obtained when [Ni(rac-L)](ClO4)2 reacted with l-cysteine under weakly basic conditions in the air. We found that the macrocyclic nickel(II) complexes can easily take up and fix atmospheric CO2 at room temperature. Single-crystal X-ray diffraction analyses revealed of all three complexes that the central Ni(II) atoms all have a six-coordinated distorted octahedral coordination geometry, and the carbonate anion bridges two Ni(II) atoms in a tridentate fashion to form dimers in complexes 1 and 2, and the hydrocarbonate coordinates with Ni(II) in a didentate fashion in complex 3. The monomers of {[Ni(RR-L)]2(µ-CO3)(H2O)}2+/{[Ni(SS-L)]2(µ-CO3)(H2O)}2+ are connected through hydrogen bonds to generate one-dimensional right- and left-handed helical chains in complex 1. The chiral nature of complex 2 has been confirmed by CD spectroscopy.

1 citations

References
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Journal ArticleDOI
TL;DR: The first homochiral binuclear metal complex cation-containing inorganic-organic hybrid chalcogenidometalates [Ni2(teta)3]-Ge4S10·H2O (1 and 1′; teta = triethylenetetramine) were prepared, which spontaneously separate in enantiomers upon crystallization; a unique water-mediated hybrid supramolecular helix, and correlation between molecular chirality and absolute helicity are observed in the entantiomers as mentioned in this paper.
Abstract: The first homochiral binuclear metal complex cation-containing inorganic–organic hybrid chalcogenidometalates [Ni2(teta)3](Ge4S10)·H2O (1 and 1′; teta = triethylenetetramine) were prepared, which spontaneously separate in enantiomers upon crystallization; a unique water-mediated hybrid supramolecular helix, and the correlation between molecular chirality and absolute helicity are observed in the entantiomers.

36 citations

Journal ArticleDOI
TL;DR: Two isomers of [Ni(α-rac-L)](ClO 4 ) 2 were prepared, and their configurations and reaction properties were investigated in this article, where they were shown to be stable with HBDC and pyca ligands.
Abstract: Two isomers of [Ni(α-rac-L)](ClO 4 ) 2 and [Ni(β'-rac-L)](ClO 4 ) 2 were prepared, and their configurations and reaction properties were investigated (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). Reactions of [Ni(α-rac-L)](ClO 4 ) 2 isomer with HBDC - , BDC 2- , and pyca - ligands give six-coordinated cis-nickel(II) complexes of cis-[Ni(f-rac-L)(HBDC)](ClO 4 ) 1, cis-{[Ni(f-rac-L)]2(BDC)(H 2 O)}(H20)2(ClO 4 ) 2 2, and cis-[Ni(f-rac-L-(pyca)](ClO 4 )4, where BDC = trans-butene dicarboxylate and pyca = 4-pyridinecarboxylate. Reactions of [Ni(β'-rac-L)](ClO 4 ) 2 isomer with HBDC - and pyca - lead to six-coordinated trans-nickel(II) complexes of {trans-[Ni(meso-L)(BDC)](H 2 BDC)} n 3 and trans-[Ni(meso-L)(pyca)2] (H 2 O) 2 5. Single-crystal X-ray diffraction analyses reveal that 1 and 4 form one-dimensional (1D) zigzag chains via the intermolecular hydrogen bonds, 2 is a dimer of two [NiL] 2+ units bridged by one BDC 2- anion, 3 forms a two-dimensional layer structure of BDCH 2 molecules hydrogen bonded with 1D chains of [Ni(meso-L)(BDC)] n , and 5 is an extended hydrogen-bonded three-dimensional network.

28 citations

Journal ArticleDOI
TL;DR: In this paper, mixed flexible and rigid achiral ligands were introduced into the chiral polyoxometalate-based skeleton, leading to the isolation of two enantiomerically 3D chiral hexadecavanadate derivatives.
Abstract: Introducing of mixed flexible and rigid achiral ligands into the hexadecavanadate skeleton leads to the isolation of two enantiomerically 3D chiral hexadecavanadate derivatives, which represent the first example of chiral polyoxometalate-based framework functionalized with mixed flexible and rigid achiral ligands.

23 citations

Journal ArticleDOI
TL;DR: The enantiopure agents d- and l-leucine, selectively bind RR and SS enantiomers from a racemate to giveDelta-/Lambda- and Delta-/S-, demonstrating the favorable stereo-coordination environments of [Ni(alpha-RR-L))(l-HLeu)], and the results of X-ray crystal structural analysis reveal that Delta- and Lambda, S- and R-, and Delta
Abstract: The enantiopure agents d- and l-leucine, selectively bind RR and SS enantiomers from a racemate [Ni(α-rac-L)]2+ to give {[Ni(RR-L)(d-HLeu)](ClO4)2}n (Δ-1) and {[Ni(SS-L)(l-HLeu)](ClO4)2}n (Λ-1), respectively, and leave the corresponding uninteracted SS and RR enantiomers of [Ni(α-SS-L)](ClO4)2 (S-2) and [Ni(α-RR-L)](ClO4)2 (R-2). Occasionally, a few crystals of {[Ni(RR-L)(l-HLeu)](ClO4)2}n (Δ-3) and {[Ni(SS-L)(d-HLeu)](ClO4)2}n (Λ-3) were found to have accreted with the crystals of Λ-1/R-2, and Δ-1/S-2, respectively (the yields are less than 2%). The results of X-ray crystal structural analysis reveal that Δ-1 and Λ-1, S-2 and R-2, and Δ-3 and Λ-3 are enantiomers, in which Δ-1 and Δ-3 possess 1D right-handed helical chains, while Λ-1 and Λ-3 exhibit a motif of 1D left-handed helical chains. The results of DFT calculations reveal that the single-point energies of [Ni(RR-L)(d-HLeu)]2+/[Ni(SS-L)(l-HLeu)]2+ in Δ-1/Λ-1 are 582 kJ mol−1 lower than those of [Ni(RR-L)(l-HLeu)]2+/[Ni(SS-L)(d-HLeu)]2+ in Δ-3/Λ-3, demonstrating the favorable stereo-coordination environments of [Ni(α-RR-L)]2+ and [Ni(α-SS-L)]2+ towards d and l-HLeu, respectively.

20 citations

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