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Published on: April 12, 2019
Calix
Frkanec1, Visnjevac, Kojic-Prodic
1Laboratory for Supramolecular and Nucleoside Chemistry, Rudjer Boskovic Institute, Zagreb, Croatia.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|April 5, 2000
Summary
New chiral calix[4]arene derivatives with phenylglycine (Phg) or leucine (Leu) strands exhibit stable conformations. These molecules demonstrate selective metal cation binding and transport due to organized cavities formed by hydrogen bonds.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Host-Guest Chemistry
Background:
- Calix[4]arene derivatives are versatile macrocyclic hosts with tunable properties.
- Hydrogen bonding plays a crucial role in organizing molecular cavities and influencing host-guest interactions.
Purpose of the Study:
- To synthesize novel chiral calix[4]arene derivatives incorporating N-acetyl-phenylglycine (Phg) or N-acetyl-leucine (Leu) ester strands.
- To investigate the conformational behavior, hydrogen bonding patterns, and metal cation binding/transport properties of these new derivatives.
Main Methods:
- Synthesis of chiral calix[4]arene derivatives with varying numbers and positions of functionalized strands.
- Solution-state conformational analysis using NMR spectroscopy in chloroform.
- X-ray crystallography for detailed solid-state structural determination.
- Investigation of metal cation selectivity and extraction/transport properties.
Main Results:
- Compounds 1 and 2 (fully substituted) adopt stable cone conformations stabilized by circular interstrand hydrogen bonds, influencing cation selectivity.
- Partially substituted derivatives (3, 4, 5) exhibit diverse conformations (stabilized cone, time-averaged C2, flattened cone) dictated by specific hydrogen bonding motifs.
- X-ray analysis of 1 reveals C2 symmetry and self-assembly into infinite chains via hydrogen bonds.
- The [1-Na]ClO4 complex shows identical solution and solid-state structures with C4 symmetry in a cone conformation.
Conclusions:
- Chiral calix[4]arene derivatives can be designed to form organized cavities through hydrogen bonding, enabling selective metal cation recognition.
- The degree and pattern of substitution significantly impact the conformational preferences and supramolecular assembly of these macrocycles.
- These findings contribute to the development of novel host molecules for ion sensing and separation applications.
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