Single Molecule Force Spectroscopy of self complementary hydrogen-bonded supramolecular systems: dimers, polymers and solvent effects

A. Embrechts

Research output: ThesisPhD Thesis - Research UT, graduation UT

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Abstract

The work described in this Thesis aimed at a better understanding of the structure-property relationships of supramolecular assemblies with a specific focus on hydrogen-bond dimers and polymers. The hydrogen-bond strength of (supra)molecular complexes in different solvents is usually determined by measuring the concentration dependent transition of dimers to monomers in the solvent of interest, e.g. with isothermal titration calorimetry (ITC) or nuclear magnetic resonance spectroscopy (NMR). However, these ensemble averaging methods may hide interesting effects, such as unresolved transition states or the influence of molecular aggregates in solution. They are also not applicable for complexes formed at low concentrations. Since supramolecular hydrogen-bonded systems are nowadays used and further developed as building blocks e.g. for self-healing polymers and molecular motors, single molecule measurements can provide new molecular level insight to support this development for future applications. Furthermore single molecule investigations are interesting from a fundamental point of view due to the disparity of theoretical calculations and bulk measurements of equilibrium dimerization constants Kdim observed in several of these systems. The experimental work described in this Thesis covers the synthesis and characterization of self-assembling supramolecular hydrogen-bonded arrays in the bulk as well as at surfaces. In particular atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS) was used to investigate the energy landscape of the hydrogen-bonds in ureidopyrimidinone (UPy) and urea-aminotriazine (UAT) dimers and polymers in different solvents (2-propanol, 1-nonanol and hexadecane). Exploiting the Kramers-Bell-Evans approach, this technique directly yields equilibrium dimerization constants Kdim based on the measured bond strength values at different bond loading rates (stretching rates) of individual molecules, provided that an estimate for the on rate of the complex formation or the diffusive relaxation time is known. The formation and bond failure of supramolecular polymers of the two self-complementary quadruple hydrogen-bonded arrays is successfully studied as well. The rupture force observed as a function of the number of linkers N is in quantitative agreement with the theory on uncooperative bond rupture for supramolecular linkages switched in a series, which provides a new approach to determine the relevant kinetic parameters from SMFS measurements at one single loading rate.
Original languageEnglish
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Vancso, Gyula J., Supervisor
  • Schönherr, Holger, Advisor
Award date19 May 2011
Place of PublicationEnschede
Publisher
Print ISBNs978 905 335 400 1
Publication statusPublished - 19 May 2011

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Dimers
Hydrogen
Polymers
Spectroscopy
Hydrogen bonds
Molecules
Dimerization
2-Propanol
Calorimetry
Titration
Kinetic parameters
Relaxation time
Nuclear magnetic resonance spectroscopy
Stretching
Urea
Atomic force microscopy
Monomers

Keywords

  • METIS-278549
  • IR-77050

Cite this

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title = "Single Molecule Force Spectroscopy of self complementary hydrogen-bonded supramolecular systems: dimers, polymers and solvent effects",
abstract = "The work described in this Thesis aimed at a better understanding of the structure-property relationships of supramolecular assemblies with a specific focus on hydrogen-bond dimers and polymers. The hydrogen-bond strength of (supra)molecular complexes in different solvents is usually determined by measuring the concentration dependent transition of dimers to monomers in the solvent of interest, e.g. with isothermal titration calorimetry (ITC) or nuclear magnetic resonance spectroscopy (NMR). However, these ensemble averaging methods may hide interesting effects, such as unresolved transition states or the influence of molecular aggregates in solution. They are also not applicable for complexes formed at low concentrations. Since supramolecular hydrogen-bonded systems are nowadays used and further developed as building blocks e.g. for self-healing polymers and molecular motors, single molecule measurements can provide new molecular level insight to support this development for future applications. Furthermore single molecule investigations are interesting from a fundamental point of view due to the disparity of theoretical calculations and bulk measurements of equilibrium dimerization constants Kdim observed in several of these systems. The experimental work described in this Thesis covers the synthesis and characterization of self-assembling supramolecular hydrogen-bonded arrays in the bulk as well as at surfaces. In particular atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS) was used to investigate the energy landscape of the hydrogen-bonds in ureidopyrimidinone (UPy) and urea-aminotriazine (UAT) dimers and polymers in different solvents (2-propanol, 1-nonanol and hexadecane). Exploiting the Kramers-Bell-Evans approach, this technique directly yields equilibrium dimerization constants Kdim based on the measured bond strength values at different bond loading rates (stretching rates) of individual molecules, provided that an estimate for the on rate of the complex formation or the diffusive relaxation time is known. The formation and bond failure of supramolecular polymers of the two self-complementary quadruple hydrogen-bonded arrays is successfully studied as well. The rupture force observed as a function of the number of linkers N is in quantitative agreement with the theory on uncooperative bond rupture for supramolecular linkages switched in a series, which provides a new approach to determine the relevant kinetic parameters from SMFS measurements at one single loading rate.",
keywords = "METIS-278549, IR-77050",
author = "A. Embrechts",
year = "2011",
month = "5",
day = "19",
language = "English",
isbn = "978 905 335 400 1",
publisher = "Ipskamp Printing",
address = "Netherlands",
school = "University of Twente",

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Single Molecule Force Spectroscopy of self complementary hydrogen-bonded supramolecular systems: dimers, polymers and solvent effects. / Embrechts, A.

Enschede : Ipskamp Printing, 2011. 166 p.

Research output: ThesisPhD Thesis - Research UT, graduation UT

TY - THES

T1 - Single Molecule Force Spectroscopy of self complementary hydrogen-bonded supramolecular systems: dimers, polymers and solvent effects

AU - Embrechts, A.

PY - 2011/5/19

Y1 - 2011/5/19

N2 - The work described in this Thesis aimed at a better understanding of the structure-property relationships of supramolecular assemblies with a specific focus on hydrogen-bond dimers and polymers. The hydrogen-bond strength of (supra)molecular complexes in different solvents is usually determined by measuring the concentration dependent transition of dimers to monomers in the solvent of interest, e.g. with isothermal titration calorimetry (ITC) or nuclear magnetic resonance spectroscopy (NMR). However, these ensemble averaging methods may hide interesting effects, such as unresolved transition states or the influence of molecular aggregates in solution. They are also not applicable for complexes formed at low concentrations. Since supramolecular hydrogen-bonded systems are nowadays used and further developed as building blocks e.g. for self-healing polymers and molecular motors, single molecule measurements can provide new molecular level insight to support this development for future applications. Furthermore single molecule investigations are interesting from a fundamental point of view due to the disparity of theoretical calculations and bulk measurements of equilibrium dimerization constants Kdim observed in several of these systems. The experimental work described in this Thesis covers the synthesis and characterization of self-assembling supramolecular hydrogen-bonded arrays in the bulk as well as at surfaces. In particular atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS) was used to investigate the energy landscape of the hydrogen-bonds in ureidopyrimidinone (UPy) and urea-aminotriazine (UAT) dimers and polymers in different solvents (2-propanol, 1-nonanol and hexadecane). Exploiting the Kramers-Bell-Evans approach, this technique directly yields equilibrium dimerization constants Kdim based on the measured bond strength values at different bond loading rates (stretching rates) of individual molecules, provided that an estimate for the on rate of the complex formation or the diffusive relaxation time is known. The formation and bond failure of supramolecular polymers of the two self-complementary quadruple hydrogen-bonded arrays is successfully studied as well. The rupture force observed as a function of the number of linkers N is in quantitative agreement with the theory on uncooperative bond rupture for supramolecular linkages switched in a series, which provides a new approach to determine the relevant kinetic parameters from SMFS measurements at one single loading rate.

AB - The work described in this Thesis aimed at a better understanding of the structure-property relationships of supramolecular assemblies with a specific focus on hydrogen-bond dimers and polymers. The hydrogen-bond strength of (supra)molecular complexes in different solvents is usually determined by measuring the concentration dependent transition of dimers to monomers in the solvent of interest, e.g. with isothermal titration calorimetry (ITC) or nuclear magnetic resonance spectroscopy (NMR). However, these ensemble averaging methods may hide interesting effects, such as unresolved transition states or the influence of molecular aggregates in solution. They are also not applicable for complexes formed at low concentrations. Since supramolecular hydrogen-bonded systems are nowadays used and further developed as building blocks e.g. for self-healing polymers and molecular motors, single molecule measurements can provide new molecular level insight to support this development for future applications. Furthermore single molecule investigations are interesting from a fundamental point of view due to the disparity of theoretical calculations and bulk measurements of equilibrium dimerization constants Kdim observed in several of these systems. The experimental work described in this Thesis covers the synthesis and characterization of self-assembling supramolecular hydrogen-bonded arrays in the bulk as well as at surfaces. In particular atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS) was used to investigate the energy landscape of the hydrogen-bonds in ureidopyrimidinone (UPy) and urea-aminotriazine (UAT) dimers and polymers in different solvents (2-propanol, 1-nonanol and hexadecane). Exploiting the Kramers-Bell-Evans approach, this technique directly yields equilibrium dimerization constants Kdim based on the measured bond strength values at different bond loading rates (stretching rates) of individual molecules, provided that an estimate for the on rate of the complex formation or the diffusive relaxation time is known. The formation and bond failure of supramolecular polymers of the two self-complementary quadruple hydrogen-bonded arrays is successfully studied as well. The rupture force observed as a function of the number of linkers N is in quantitative agreement with the theory on uncooperative bond rupture for supramolecular linkages switched in a series, which provides a new approach to determine the relevant kinetic parameters from SMFS measurements at one single loading rate.

KW - METIS-278549

KW - IR-77050

M3 - PhD Thesis - Research UT, graduation UT

SN - 978 905 335 400 1

PB - Ipskamp Printing

CY - Enschede

ER -