Topomeric aza/thia cryptands: Synthesis and theoretical aspects of: In / out isomerism using n -alkyl bridging

Ian S. Taschner; Tia L. Walker; Sharath M. Chandra; Briana R. Schrage; Christopher J. Ziegler; Xinfeng Gao; Steven E. Wheeler

doi:10.1039/d0qo00123f

Topomeric aza/thia cryptands: Synthesis and theoretical aspects of: In / out isomerism using n -alkyl bridging

Ian S. Taschner, Tia L. Walker, Sharath M. Chandra, Briana R. Schrage, Christopher J. Ziegler, Xinfeng Gao, Steven E. Wheeler

Research output: Contribution to journal › Article › peer-review

7 Scopus citations

Abstract

A series of heterobicyclic aza/thia-lactams and cryptands incorporating changes in n-alkyl bridging length have been synthesized, characterized, chelated to heavy metals and computationally assessed. Spectroscopic analysis of aza/thia-lactams L1 and L3 revealed multiple conformational isomers, due to rotameric perturbations associated with the amide bond. Correlation spectroscopy on amine cryptands L2 and L4 supported the presence of intrinsic topological chirality, resulting from a preferred orientation of the amine lone pairs in solution. The unique magnetic environments observed in ¹H NMR were attributed to the electron density inside the crypt, which adopt a nephroidal-epicycloid structure with two nitrogen atoms representing the cusps. The major conformational and constitutional isomers for L2 and L4 present in solution were determined to be the in/in pair of enantiomers (R,R and S,S) and confirmed through computational analysis. Application of ligands L1-L4 as heavy metal chelates was addressed using Pb(ii), Hg(ii), Cd(ii) and Ag(i) through NMR spectroscopy and mass spectroscopy.

Original language	English
Pages (from-to)	1164-1176
Number of pages	13
Journal	Organic Chemistry Frontiers
Volume	7
Issue number	9
DOIs	https://doi.org/10.1039/d0qo00123f
State	Published - May 7 2020
Externally published	Yes

Funding

We thank Indiana University Mass Spectrometry Facility in Bloomington, IN for exact mass measurements. This study was also supported in part by resources and technical expertise from the Georgia Advanced Computing Resource Center, a partnership between the University of Georgia’s Office of the Vice President for Research and Office of the Vice President for Information Technology. We would also like to acknowledge the National Science Foundation (CHE-0840446) for funds used to purchase the Bruker APEX II Duo X-ray diffractometer used in this research.

Funders	Funder number
Office of the Vice President for Information Technology
National Science Foundation	CHE-0840446
Office of the Executive Vice President for Research and Partnerships, Purdue University

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title = "Topomeric aza/thia cryptands: Synthesis and theoretical aspects of: In / out isomerism using n -alkyl bridging",

abstract = "A series of heterobicyclic aza/thia-lactams and cryptands incorporating changes in n-alkyl bridging length have been synthesized, characterized, chelated to heavy metals and computationally assessed. Spectroscopic analysis of aza/thia-lactams L1 and L3 revealed multiple conformational isomers, due to rotameric perturbations associated with the amide bond. Correlation spectroscopy on amine cryptands L2 and L4 supported the presence of intrinsic topological chirality, resulting from a preferred orientation of the amine lone pairs in solution. The unique magnetic environments observed in 1H NMR were attributed to the electron density inside the crypt, which adopt a nephroidal-epicycloid structure with two nitrogen atoms representing the cusps. The major conformational and constitutional isomers for L2 and L4 present in solution were determined to be the in/in pair of enantiomers (R,R and S,S) and confirmed through computational analysis. Application of ligands L1-L4 as heavy metal chelates was addressed using Pb(ii), Hg(ii), Cd(ii) and Ag(i) through NMR spectroscopy and mass spectroscopy.",

author = "Taschner, {Ian S.} and Walker, {Tia L.} and Chandra, {Sharath M.} and Schrage, {Briana R.} and Ziegler, {Christopher J.} and Xinfeng Gao and Wheeler, {Steven E.}",

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month = may,

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doi = "10.1039/d0qo00123f",

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AU - Taschner, Ian S.

AU - Walker, Tia L.

AU - Chandra, Sharath M.

AU - Schrage, Briana R.

AU - Ziegler, Christopher J.

AU - Gao, Xinfeng

AU - Wheeler, Steven E.

PY - 2020/5/7

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N2 - A series of heterobicyclic aza/thia-lactams and cryptands incorporating changes in n-alkyl bridging length have been synthesized, characterized, chelated to heavy metals and computationally assessed. Spectroscopic analysis of aza/thia-lactams L1 and L3 revealed multiple conformational isomers, due to rotameric perturbations associated with the amide bond. Correlation spectroscopy on amine cryptands L2 and L4 supported the presence of intrinsic topological chirality, resulting from a preferred orientation of the amine lone pairs in solution. The unique magnetic environments observed in 1H NMR were attributed to the electron density inside the crypt, which adopt a nephroidal-epicycloid structure with two nitrogen atoms representing the cusps. The major conformational and constitutional isomers for L2 and L4 present in solution were determined to be the in/in pair of enantiomers (R,R and S,S) and confirmed through computational analysis. Application of ligands L1-L4 as heavy metal chelates was addressed using Pb(ii), Hg(ii), Cd(ii) and Ag(i) through NMR spectroscopy and mass spectroscopy.

AB - A series of heterobicyclic aza/thia-lactams and cryptands incorporating changes in n-alkyl bridging length have been synthesized, characterized, chelated to heavy metals and computationally assessed. Spectroscopic analysis of aza/thia-lactams L1 and L3 revealed multiple conformational isomers, due to rotameric perturbations associated with the amide bond. Correlation spectroscopy on amine cryptands L2 and L4 supported the presence of intrinsic topological chirality, resulting from a preferred orientation of the amine lone pairs in solution. The unique magnetic environments observed in 1H NMR were attributed to the electron density inside the crypt, which adopt a nephroidal-epicycloid structure with two nitrogen atoms representing the cusps. The major conformational and constitutional isomers for L2 and L4 present in solution were determined to be the in/in pair of enantiomers (R,R and S,S) and confirmed through computational analysis. Application of ligands L1-L4 as heavy metal chelates was addressed using Pb(ii), Hg(ii), Cd(ii) and Ag(i) through NMR spectroscopy and mass spectroscopy.

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JO - Organic Chemistry Frontiers

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Topomeric aza/thia cryptands: Synthesis and theoretical aspects of: In / out isomerism using n -alkyl bridging

Abstract

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