Synthesis of Novel Fluorescent Probes for the Early Diagnosis of Alzheimer’s Disease

Alzheimer’s disease (AD) is a detrimental, progressive neurodegenerative disease that is regarded as the most common and pervasive form of dementia, affecting an estimated 1 in 14 people over the age of 65 and 1 in every 6 people over the age of 80.1,2 Diagnosing AD at the proper time poses a great challenge in the current clinical setting. Traditional methods for the diagnosis of AD are expensive, provide poor resolution, and involve toxic radioactive materials. This study aims to synthesize a class of novel fluorescent molecular probes that can bind to the protein-plaques that are caused by the onset of AD to ultimately provide a safe and effective method to diagnose the early stages of AD through improved in vivo imaging, potentially becoming an indispensable tool for diagnosis. The final fluorescent molecular probe was synthesized from a simple Sn2 reaction involving a precursor and was characterized using 1H and 13C nuclear magnetic resonance spectra, elemental analysis, thermogravimetric analysis, and solubility properties. The resultant fluorescent molecular probe was successfully synthesized and emits white-light fluorescence in the solution-state when dissolved in water, making it suitable for aqueous systems. Further studies can be expanded upon for in vivo imaging studies, toxicity, and suitability for the clinical setting.https://digitalscholarship.unlv.edu/durep_posters/1070/thumbnail.jp

Isothermal Titration Calorimetry and Transmission Electron Microscopy of Main-Chain Viologen Polymer Containing Bromide as Counerions

Polyelectrolytes are an important class of macromolecules that contain dissociable ionic groups. When introduced into polar solvent, usually the universal solvent water, dissociation takes place so that electrically charged macromolecule is suspended in solution. The electrostatic interaction is operative between ionized groups inside the macromolecule, between the macromolecules, between the counterions, and between the macromolecule and counterion. Since this interaction is characterized by its long-range nature, the solution exhibits various interesting properties including the polyelectrolyte behavior very different from solutions of neutral polymers

Ionic liquid crystals : synthesis and characterization via NMR, DSC, POM, X-ray diffraction and ionic conductivity of asymmetric viologen bistriflimide salts

Acknowledgments This research is in part supported by the NSF EPSCoR RING-TRUE III grant no. 0447416, NSF-SBIR grant no. OII-0610753, NSF-STTR grant no. IIP-0740289 and NASA GRC contract no. NNX10CD25P (PKB). We thank Ronald C. G. Principe for making the Figures and Tables for this article. Acknowledgment is made to the donors of the American Chemical Society Petroleum Research Fund grant no. 59345-ND7 for partial support of this research by CMR and MRF. AMF would like to thank the Carnegie Trust for the Universities of Scotland, for the Research Incentive Grant RIG008586, the Royal Society and Specac Ltd., for the Research Grant RGS\R1\201397, and the Royal Society of Chemistry for the award of a mobility grant (M19-0000).Peer reviewedPostprin

Dicationic stilbazolium salts : structural, thermal, optical, and ionic conduction properties

Acknowledgments This research is in part supported by the NSF EPSCoR RING-TRUE III grant no. 0447416, NSF-SBIR grant no. OII-0610753, NSF-STTR grant no. IIP-0740289 and NASA GRC contract no. NNX10CD25P (PKB). BD and BH thank the CNRS and University of Strasbourg. AMF would like to acknowledge the Carnegie Trust for the Universities of Scotland, for the Research Incentive Grant RIG008586, the Royal Society and Specac Ltd., for the Research Grant RGS\R1\201397, the Royal Society of Chemistry for the award of a mobility grant (M19-0000), and the Royal Society of Edinburgh and the Scottish Government, for the award of a SAPHIRE project.Peer reviewedPostprin

High Ionic Conductivities of Ionic Materials as Potential Electrolytes

Acknowledgments We sincerely acknowledge Dr. Kousaalya Bakthavatchalam for critically reading and making insightful suggestions for the improvement of the article. TSV acknowledges the Ministry of Higher Education under the Fundamental Research Grant Scheme [FRGS/1/2018/STG07/UM/02/6] for the financial support. AMF would like to thank the Carnegie Trust for the Universities of Scotland, for the Research Incentive Grant RIG008586, the Royal Society and Specac Ltd. for the Research Grant RGS\R1\201397, the Royal Society of Edinburgh and the Scottish Government for one Sapphire project, and the Royal Society of Chemistry for the award of a mobility grant (M19-0000). UB thanks the School of Engineering (University of Aberdeen) for the award of one Summer Scholarship.Publisher PD

Thermotropic Liquid-Crystalline and Light-Emitting Properties of Poly(pyridinium) Salts Containing Various Diamine Connectors and Hydrophilic Macrocounterions

A set of poly(pyridinium) salts containing various diamine moieties, as molecular connectors, and poly(ethyleneglycol)-4-nonylphenyl-3-sulfopropyl ether, thereafter referred to as “Macroion”, as the hydrophilic counterion, were prepared by metathesis reaction from the respective precursory tosylated poly(pyridinium)s in methanol. The structure of these ionic polymers was established by spectroscopy and chromatography techniques. The shape-persistent ionic poly(pyridinium) materials, inserting rigid or semi-rigid diamine spacers, display thermotropic liquid-crystalline properties from room-temperature up to their isotropization (in the temperature range around 160–200 °C). The nature of the LC phases is lamellar in both cases as identified by the combination of various complementary experimental techniques including DSC, POM and variable-temperature SAXS. The other polymers, inserting bulky or flexible spacers, only form room temperature viscous liquids. These new macromolecular systems can then be referred to as polymeric ionic liquid crystals (PILCs) and or polymeric ionic liquids (PILs). All the ionic polymers show excellent thermal stability, in the 260–330 °C temperature range as determined by TGA measurements, and a good solubility in common organic solvents as well as in water. Their optical properties were characterized in both solution and solid states by UV−Vis and photoluminescent spectroscopies. They emit blue or green light in both the states and exhibit a positive solvatochromic effect

Thermotropic Liquid-Crystalline Properties of Viologens Containing 4-n-alkylbenzenesulfonates†

A series of viologens containing 4-n-alkylbenzenesulfonates were synthesized by the metathesis reaction of 4-n-alkylbenzenesulfonic acids or sodium 4-n-alkylbezenesulfonates with the respective viologen dibromide in alcohols. Their chemical structures were characterized by Fourier Transform Infrared, 1H and 13C Nuclear Magnetic Resonance spectra and elemental analysis. Their thermotropic liquid-crystalline (LC) properties were examined by differential scanning calorimetry and polarizing optical microscopy. They formed LC phases above their melting transitions and showed isotropic transitions. As expected, all the viologen salts had excellent stabilities in the temperature range of 278–295 °C as determined by thermogravimetric analysis

Synthesis, Optical, and Thermal Properties of 2,4,6-Tris(4-Substituted Phenyl)Pyrylium Tosylates And Triflimides

A group of five 2,4,6-tris(4-substituted phenyl)pyrylium tosylates were synthesized in one-pot reaction from para-substituted benzaldehyde and para-substituted acetophenones using tosic acid as a condensing agent. The tosylate salts were converted to the corresponding triflimide salts by metathesis reactions. Chemical structures, as well as optical spectroscopic and thermal properties of these salts were studied using pertinent experimental techniques. Trimethyl- and trihalo-substituted pyrylium salts emitted strong blue light with peaks in the 456 nm–479 nm range and trimethoxy-pyrylium salts emitted intense green light with maxima around 526 nm in acetonitrile solution. Quantum yields of the solutions were rather low, but the salts were also fluorescent in the solid state. Acetonitrile solution of trichloro-substituted pyrylium triflimide showed significant spectral line narrowing and fluorescence lifetime shortening under intense excitation, and laser action with minimal feedback. The salts have low melting transitions compared to the corresponding –BF4 salts, and their thermal stability is excellent with decomposition temperature in the 268–402 °C range in nitrogen

Dicationic Stilbazolium Salts: Structural, Thermal, Optical, and Ionic Conduction Properties

Two series of new dicationic stilbazolium salts containing tosylate and triflimide counterions, respectively, were synthesized and characterized by spectroscopic techniques and elemental analysis. Despite of their promesogenic structures, none of these salts are mesomorphous, and instead they solely exhibit crystalline polymorphism, as deduced from differential scanning calorimetry, polarizing optical microscopy and variable temperature X-ray measurements. These salts were also found to be highly thermally stable with decomposition temperatures occurring well above 300 °C, and up to 367 °C for the triflimide salts, as determined by thermogravimetric analysis. UV–Vis absorption and photoluminescent properties were examined in both solution and in the solid state. They exhibited higher absolute quantum yields in the powdered state than in solution. The dielectric response was evaluated by impedance spectroscopy, revealing notable values of short-range conductivity in triflimide salts through amorphous regions. Our work demonstrates the potential of these new stilbazolium salts as advanced materials in optoelectronic devices, with performances that can be tailored by molecular design of the spacer\u27s flexibility and choice of counter anions

Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9\u27-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (1H), and fluorine 19 (19F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (Mns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12-1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60-80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λem peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0-90%), and their λem peaks were blue shifted