International Journal of Molecular Sciences

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1880 KiB

Open AccessArticle

Mesoscale Characterization of Supramolecular Transient Networks Using SAXS and Rheology

by A. C. H. Pape, Maartje M. C. Bastings, Roxanne E. Kieltyka, Hans M. Wyss, Ilja K. Voets, E. W. Meijer and Patricia Y. W. Dankers

Int. J. Mol. Sci. 2014, 15(1), 1096-1111; https://doi.org/10.3390/ijms15011096 - 16 Jan 2014

Cited by 39 | Viewed by 8570

Abstract

Hydrogels and, in particular, supramolecular hydrogels show promising properties for application in regenerative medicine because of their ability to adapt to the natural environment these materials are brought into. However, only few studies focus on the structure-property relationships in supramolecular hydrogels. Here, we [...] Read more.

Hydrogels and, in particular, supramolecular hydrogels show promising properties for application in regenerative medicine because of their ability to adapt to the natural environment these materials are brought into. However, only few studies focus on the structure-property relationships in supramolecular hydrogels. Here, we study in detail both the structure and the mechanical properties of such a network, composed of poly(ethylene glycol), end-functionalized with ureido-pyrimidinone fourfold hydrogen bonding units. This network is responsive to triggers such as concentration, temperature and pH. To obtain more insight into the sol-gel transition of the system, both rheology and small-angle X-ray scattering (SAXS) are used. We show that the sol-gel transitions based on these three triggers, as measured by rheology, coincide with the appearance of a structural feature in SAXS. We attribute this feature to the presence of hydrophobic domains where cross-links are formed. These results provide more insight into the mechanism of network formation in these materials, which can be exploited for tailoring their behavior for biomedical applications, where one of the triggers discussed might be used. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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1558 KiB

Open AccessArticle

Synthesis and Characterization of β-Cyclodextrin Functionalized Ionic Liquid Polymer as a Macroporous Material for the Removal of Phenols and As(V)

by Muggundha Raoov, Sharifah Mohamad and Mhd Radzi Abas

Int. J. Mol. Sci. 2014, 15(1), 100-119; https://doi.org/10.3390/ijms15010100 - 23 Dec 2013

Cited by 79 | Viewed by 11434

Abstract

β-Cyclodextrin-ionic liquid polymer (CD-ILP) was first synthesized by functionalized β-cyclodextrin (CD) with 1-benzylimidazole (BIM) to form monofunctionalized CD (βCD-BIMOTs) and was further polymerized using a toluene diisocyanate (TDI) linker to form insoluble CD-ILP (βCD-BIMOTs-TDI). The βCD-BIMOTs-TDI polymer was characterized using various tools and [...] Read more.

β-Cyclodextrin-ionic liquid polymer (CD-ILP) was first synthesized by functionalized β-cyclodextrin (CD) with 1-benzylimidazole (BIM) to form monofunctionalized CD (βCD-BIMOTs) and was further polymerized using a toluene diisocyanate (TDI) linker to form insoluble CD-ILP (βCD-BIMOTs-TDI). The βCD-BIMOTs-TDI polymer was characterized using various tools and the results obtained were compared with those derived from the native β-cyclodextrin polymer (βCD-TDI). The SEM result shows that the presence of ionic liquid (IL) increases the pore size, while the thermo gravimetric analysis (TGA) result shows that the presence of IL increases the stability of the polymer. Meanwhile, Brunauer-Emmett-Teller (BET) results show that βCD-BIMOTs-TDI polymer has 1.254 m²/g surface areas and the Barret-Joyner-Halenda (BJH) pore size distribution result reveals that the polymer exhibits macropores with a pore size of 77.66 nm. Preliminary sorption experiments were carried out and the βCD-BIMOTs-TDI polymer shows enhanced sorption capacity and high removal towards phenols and As(V). Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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1137 KiB

Open AccessArticle

New Mononuclear Cu(II) Complexes and 1D Chains with 4-Amino-4H-1,2,4-triazole

by Marinela M. Dîrtu, Yves Boland, Damien Gillard, Bernard Tinant, Koen Robeyns, Damir A. Safin, Eamonn Devlin, Yiannis Sanakis and Yann Garcia

Int. J. Mol. Sci. 2013, 14(12), 23597-23613; https://doi.org/10.3390/ijms141223597 - 3 Dec 2013

Cited by 14 | Viewed by 6559

Abstract

The crystal structures of two mononuclear Cu(II) NH₂trz complexes [Cu(NH₂trz)₄(H₂O)](AsF₆)₂ (I) and [Cu(NH₂trz)₄(H₂O)](PF₆)₂ (II) as well as two coordination [...] Read more.

The crystal structures of two mononuclear Cu(II) NH₂trz complexes [Cu(NH₂trz)₄(H₂O)](AsF₆)₂ (I) and [Cu(NH₂trz)₄(H₂O)](PF₆)₂ (II) as well as two coordination polymers [Cu(μ₂-NH₂trz)₂Cl]Cl∙H₂O (III) and [Cu(μ₂-NH₂trz)₂Cl] (SiF₆)_0.5∙1.5H₂O (IV) are presented. Cationic 1D chains with bridging bis-monodentate μ₂-coordinated NH₂trz and bridging μ₂-coordinated chloride ligands are present in III and IV. In these coordination polymers, the Cu(II) ions are strongly antiferromagnetically coupled with J = −128.4 cm⁻¹ for III and J = −143 cm⁻¹ for IV (H = −JΣS_iS_i₊₁), due to the nature of the bridges between spin centers. Inter-chain interactions present in the crystal structures were taken into consideration, as well as g factors, which were determined experimentally, for the quantitative modeling of their magnetic properties. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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646 KiB

Open AccessArticle

Supramolecular Luminescence from Oligofluorenol-Based Supramolecular Polymer Semiconductors

by Guang-Wei Zhang, Long Wang, Ling-Hai Xie, Jin-Yi Lin and Wei Huang

Int. J. Mol. Sci. 2013, 14(11), 22368-22379; https://doi.org/10.3390/ijms141122368 - 13 Nov 2013

Cited by 8 | Viewed by 6172

Abstract

Supramolecular luminescence stems from non-covalent exciton behaviors of active π-segments in supramolecular entities or aggregates via intermolecular forces. Herein, a π-conjugated oligofluorenol, containing self-complementary double hydrogen bonds, was synthesized using Suzuki coupling as a supramolecular semiconductor. Terfluorenol-based random supramolecular polymers were confirmed via [...] Read more.

Supramolecular luminescence stems from non-covalent exciton behaviors of active π-segments in supramolecular entities or aggregates via intermolecular forces. Herein, a π-conjugated oligofluorenol, containing self-complementary double hydrogen bonds, was synthesized using Suzuki coupling as a supramolecular semiconductor. Terfluorenol-based random supramolecular polymers were confirmed via concentration-dependent nuclear magnetic resonance (NMR) and dynamic light scattering (DLS). The photoluminescent spectra of the TFOH-1 solution exhibit a green emission band (g-band) at approximately ~520 nm with reversible features, as confirmed through titration experiments. Supramolecular luminescence of TFOH-1 thin films serves as robust evidence for the aggregates of g-band. Our results suggest that the presence of polyfluorene ketone defects is a sufficient condition, rather than a sufficient-necessary condition for the g-band. Supramolecular electroluminescence will push organic devices into the fields of supramolecular optoelectronics, spintronics, and mechatronics. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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486 KiB

Open AccessArticle

Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles

by Jia-ying Xin, Dan-dan Cheng, Lan-xuan Zhang, Kai Lin, Hong-chen Fan, Yan Wang and Chun-gu Xia

Int. J. Mol. Sci. 2013, 14(11), 21676-21688; https://doi.org/10.3390/ijms141121676 - 1 Nov 2013

Cited by 36 | Viewed by 8413

Abstract

Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au [...] Read more.

Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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1608 KiB

Open AccessArticle

Multivalent Protein Assembly Using Monovalent Self-Assembling Building Blocks

by Katja Petkau-Milroy, Michael H. Sonntag, Alexander Colditz and Luc Brunsveld

Int. J. Mol. Sci. 2013, 14(10), 21189-21201; https://doi.org/10.3390/ijms141021189 - 22 Oct 2013

Cited by 7 | Viewed by 7701

Abstract

Discotic molecules, which self-assemble in water into columnar supramolecular polymers, emerged as an alternative platform for the organization of proteins. Here, a monovalent discotic decorated with one single biotin was synthesized to study the self-assembling multivalency of this system in regard to streptavidin. [...] Read more.

Discotic molecules, which self-assemble in water into columnar supramolecular polymers, emerged as an alternative platform for the organization of proteins. Here, a monovalent discotic decorated with one single biotin was synthesized to study the self-assembling multivalency of this system in regard to streptavidin. Next to tetravalent streptavidin, monovalent streptavidin was used to study the protein assembly along the supramolecular polymer in detail without the interference of cross-linking. Upon self-assembly of the monovalent biotinylated discotics, multivalent proteins can be assembled along the supramolecular polymer. The concentration of discotics, which influences the length of the final polymers at the same time dictates the amount of assembled proteins. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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557 KiB

Open AccessArticle

Supramolecular Interactions of Terpyridine-Derived Cores of Metallomesogen Precursors

by Young Hoon Lee, Jack M. Harrowfield, Jong Won Shin, Mi Seon Won, Elisabeth Rukmini, Shinya Hayami, Kil Sik Min and Yang Kim

Int. J. Mol. Sci. 2013, 14(10), 20729-20743; https://doi.org/10.3390/ijms141020729 - 15 Oct 2013

Cited by 6 | Viewed by 6697

Abstract

Use of Hirshfeld surfaces calculated from crystal structure determinations on various transition metal ion complexes of three terpyridine ligands carrying trimethoxyphenyl substituents has enabled an assessment of the contribution made by the ligand components to the interactions determining the lattice structures, interactions expected [...] Read more.

Use of Hirshfeld surfaces calculated from crystal structure determinations on various transition metal ion complexes of three terpyridine ligands carrying trimethoxyphenyl substituents has enabled an assessment of the contribution made by the ligand components to the interactions determining the lattice structures, interactions expected also to be present in metallomesogens derived from similar ligands. The form of the link joining the trimethoxyphenyl substituent to the 4' position of 2,2';6',2''-terpyridine is of some importance. In the case of the Co(II) complexes of two of the ligands, their spin-crossover characteristics can be rationalised in terms of the different interactions seen in their lattices. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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1366 KiB

Open AccessArticle

Covalent Coupling of Nanoparticles with Low-Density Functional Ligands to Surfaces via Click Chemistry

by Ina Rianasari, Michel P. De Jong, Jurriaan Huskens and Wilfred G. Van der Wiel

Int. J. Mol. Sci. 2013, 14(2), 3705-3717; https://doi.org/10.3390/ijms14023705 - 7 Feb 2013

Cited by 11 | Viewed by 8723

Abstract

We demonstrate the application of the 1,3-dipolar cycloaddition (“click” reaction) to couple gold nanoparticles (Au NPs) functionalized with low densities of functional ligands. The ligand coverage on the citrate-stabilized Au NPs was adjusted by the ligand:Au surface atom ratio, while maintaining the colloidal [...] Read more.

We demonstrate the application of the 1,3-dipolar cycloaddition (“click” reaction) to couple gold nanoparticles (Au NPs) functionalized with low densities of functional ligands. The ligand coverage on the citrate-stabilized Au NPs was adjusted by the ligand:Au surface atom ratio, while maintaining the colloidal stability of the Au NPs in aqueous solution. A procedure was developed to determine the driving forces governing the selectivity and reactivity of citrate-stabilized and ligand-functionalized Au NPs on patterned self-assembled monolayers. We observed selective and remarkably stable chemical bonding of the Au NPs to the complimentarily functionalized substrate areas, even when estimating that only 1–2 chemical bonds are formed between the particles and the substrate. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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1412 KiB

Open AccessArticle

Analysis of the Enhanced Stability of R(+)-Alpha Lipoic Acid by the Complex Formation with Cyclodextrins

by Naoko Ikuta, Hironori Sugiyama, Hiroshi Shimosegawa, Rie Nakane, Yoshiyuki Ishida, Yukiko Uekaji, Daisuke Nakata, Kathrin Pallauf, Gerald Rimbach, Keiji Terao and Seiichi Matsugo

Int. J. Mol. Sci. 2013, 14(2), 3639-3655; https://doi.org/10.3390/ijms14023639 - 7 Feb 2013

Cited by 46 | Viewed by 10121

Abstract

R(+)-alpha lipoic acid (RALA) is one of the cofactors for mitochondrial enzymes and, therefore, plays a central role in energy metabolism. RALA is unstable when exposed to low pH or heat, and therefore, it is difficult to use enantiopure RALA as a pharma- [...] Read more.

R(+)-alpha lipoic acid (RALA) is one of the cofactors for mitochondrial enzymes and, therefore, plays a central role in energy metabolism. RALA is unstable when exposed to low pH or heat, and therefore, it is difficult to use enantiopure RALA as a pharma- and nutra-ceutical. In this study, we have aimed to stabilize RALA through complex formation with cyclodextrins (CDs). α-CD, β-CD and γ-CD were used for the formation of these RALA-CD complexes. We confirmed the complex formation using differential scanning calorimetry and showed by using HPLC analysis that complexed RALA is more stable than free RALA when subjected to humidity and high temperature or acidic pH conditions. Scanning electron microscopy studies showed that the particle size and shape differed depending on the cyclodextrin used for complexation. Further, the complexes of CD and RALA showed a different particle size distribution pattern compared with that of CD itself or that of the physical mixture of RALA and CD. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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Review

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2023 KiB

Open AccessReview

Solid Lipid Nanoparticle-Based Calix[n]arenes and Calix-Resorcinarenes as Building Blocks: Synthesis, Formulation and Characterization

by Imed Montasser, Patrick Shahgaldian, Florent Perret and Anthony W. Coleman

Int. J. Mol. Sci. 2013, 14(11), 21899-21942; https://doi.org/10.3390/ijms141121899 - 5 Nov 2013

Cited by 22 | Viewed by 9716

Abstract

Solid lipid nanoparticles (SLNs) have attracted increasing attention during recent years. This paper presents an overview about the use of calix[n]arenes and calix-resorcinarenes in the formulation of SLNs. Because of their specific inclusion capability both in the intraparticle spaces and in the host [...] Read more.

Solid lipid nanoparticles (SLNs) have attracted increasing attention during recent years. This paper presents an overview about the use of calix[n]arenes and calix-resorcinarenes in the formulation of SLNs. Because of their specific inclusion capability both in the intraparticle spaces and in the host cavities as well as their capacity for functionalization, these colloidal nanostructures represent excellent tools for the encapsulation of different active pharmaceutical ingredients (APIs) in the area of drug targeting, cosmetic additives, contrast agents, etc. Various synthetic routes to the supramolecular structures will be given. These various routes lead to the formulation of the corresponding SLNs. Characterization, properties, toxicological considerations as well as numerous corresponding experimental studies and analytical methods will be also exposed and discussed. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Supramolecular Systems)

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