Tetraphosphonic acid functionalized perylenediimide derivative: Synthesis and pH dependent photophysical properties

The synthesis of phosphonic acid functionalized perylene diimide (PDI) molecular architecture has been demonstrated via functionalization at imide position. UV-Vis absorption and fluorescence emission spectroscopic techniques have been employed to investigate the photophysical properties of the novel PDI derivative at different pH (2 to 11). These results demonstrate the fascinating photophysical characteristics based on change in pH from 7 to 2 and 7 to 11 in aqueous medium

pH Dependent Molecular Self-Assembly of Octaphosphonate Porphyrin of Nanoscale Dimensions: Nanosphere and Nanorod Aggregates

Self-assembled nanostructures of zwitterionic octaphosphanatoporphyrin 1, of either nanoparticles or nanorods, depending on small changes in the pH, is demonstrated based on the J-aggregates. Porphyrin 1 self-assembled into nanosphere aggregates with a diameter of about 70–80 nm in the pH range 5–7, and nanorod aggregates were observed at pH 8.5. Hydrogen bonding, π-π stacking and hydrophilic interactions play important roles in the formation of this nanostructure morphology. Nanostructures were characterized by UV/Vis absorbance, fluorescence, atomic force microscopy (AFM) and transmission electron microscopy (TEM). This interesting pH dependent self-assembly phenomenon could provide a basis for development of novel biomaterials

An efficient naphthalimide based receptor for selective detection of Hg2+and Pb2+ions

Naphthalimide based receptor 1 with N-substituted benzothiazole and pyrrolidine subunit is designed, synthesized, and characterized using FT-IR,1H and 13C NMR spectroscopy and mass spectrometry techniques. The receptor 1 exhibits prominent optical response for Hg2+and Pb2+ions allowing the detection of these ions in acetonitrile (ACN). The formation of the receptor 1:cation complexes have been investigated using UV-Vis and fluorescence emission titration. Further, the selectivity of the receptor 1towards Hg2+and Pb2+ ions on the presence of various interfering cations such as Mg2+, Ba2+, Ni2+, Co2+, Cu2+, Ag2+, Fe2+, Fe3+and Cr3+ has been confirmed by UV-Vis and fluorescence spectroscopy. The binding constant between receptor 1 and Hg2+ and Pb2+ was estimated by Benesi-Hildebrand plot and equations. The binding constants have been found to be Ka= 3.43286 ´ 10−6 and Ka= 2.84079 ´ 10−6 M for Hg2+ and Pb2+, respectively. The limit of detection (LOD) for Hg2+and Pb2+by receptor 1are down to 7.44 ´ 10−10 M and 1.26 ´ 10−9 M, respectively. In addition, Job’s plot analysis reveals 1:2 binding stoichiometry between the receptor 1 and Pb2+ and Hg2+ cations.

Rigid-rod push–pull naphthalenediimide photosystems

Design, synthesis and evaluation of advanced rigid-rod π-stack photosystems with asymmetric scaffolds are reported. The influence of push–pull rods on self-organization, photoinduced charge separation and photosynthetic activity is investigated and turns out to be surprisingly small overall

Synthese von Bolaamphiphilen und Yoktobrunnen mit Porphyrinboden auf aminierten Kieselgelpartikeln mit photoaktiven Fern-Redox-Paaren und starrer Kruste

Title 1\. Introduction 1 2\. Synthesis of yoctowell constituents 11 3\. Preparation of Aminated Silica Colloidal Particles 40 4\. Fluorescence quenching and size selective heterodimerization of a porphyrin in the yoctowells 48 5\. Immobile Crust 72 6\. Charge Separation 91 7\. Conclusion 108 8\. Experimental Part 114 9\. References 156 10\. Curriculum vitae for thesisA series of olefinic bolaamphiphiles was synthesized to produce rigid monolayers with nanometer gaps on aminated silica particles, which can be functionalized from the water phase. They contained an activated carbon-carbon double bond (bolaamphiphile 10 or bolaamphiphile 16). The double bond in 10 and 16 was introduced by a Horner-Emmons-reaction between phosphorylated butylacetate and 12-formyldodecane acid and 6-formyl hexanoic acid respectively. Monodisperse, colloidal silica spheres were prepared from tetrethoxysilane (TEOS) in mixtures of ammonia, water and ethanol. The surface of the particles could be coated through a subsequent chemical reaction with the silane coupling agent (3-aminopropyl)-triethoxysilane (APS). APS then forms a propyl amine coating on the silica particles which stabilizes them against water and organic solvents and render the surface reactive forward with acid derivatives. Spherical particles with a diameter between 20 nm and 150 nm depending on the concentration and hydrolysis time. The smaller 20 nm particles showed, however, a rough surface in transmission electron microscopy (TEM) which was not appropriate for the self-assembly of rigid membranes and defined nanometer gaps. The smallest uniform particles with a perfectly smooth surface had a uniform diameter of 100 ± 10 nm and it produced in gram scale. In order to produce rigid membranes the meta-tetracarboxy porphyrin 26 activated with ethylchloroformate 26b was fixed on aminated silica by amidation reaction, first step self-assembly in dichloromethane the mixture was stirred for 2 h. no domains were thus formed. The second self-assembly procedure step, the fixation of the bolaamphiphiles 10 or 16, were given. The membrane coated nanoparticles were isolated by repeated centrifugation, dispersion, and ultrasonification using CH2Cl2 as solvent and were used for further measurements. A monolayer with a height of 10 Å for bola 10 and 5 Å for bola 16, containing gaps of a 22 Å diameter, was obtained. The porphyrins on the bottom of the gaps could be easily detected after the second self- assembly procedure by UV/vis, fluorescence spectroscopy. The porous membranes were then examined by a fluorescence spectrometer for porphyrin fluorescence. There was no apparent difference in fluorescence intensity before and after the second self-assembly procedure. After addition of Mn(III)TPPS 27, this fluorescence was extinguished quantitatively. If the Michael double bond of bola 10 or 16 was aminated in the aqueous water volume by means of a 0.5 molar methylamine solvent. Mn(III)TPPS 27 could not enter the gap. Negatively- charged porphyrins (manganese-tetrasulfonic acid porphyrin 27) were fixed by the ring of methylammonium groups, as shown by UV/vis and fluorescence spectroscopy. The second porphyrin was localized at a distance of 10 Å and 5 Å from the first one and acted as cover for the gap. We thus succeeded to produce heterodimers with a long distance (6 and 10 Å resp.) reproducibly. This constitutes a first step towards the development of a system, which may allow charge separation with the aid of sunlight. The distance of 6 Å should be small enough to allow electron transfer from a donor to an acceptor. On the other hand, it should be large enough to prevent spontaneous recombination of charges. Charge separation experiments with noncovalent long-distance heterodimers become routine experiments using these particles and a fluorescence spectrometer. When we applied these heterodimers within the yoctowells for light induced charge separation a faster and very efficient decay mechanism with a decay time of 0.16 ns only appeared, when the manganese(III) porphyrin was attached at a distance of 5 Å. A decay time of 160 ps is in agreement with rates of electron transfers in the slowest model systems. This slowness could correspond to the unexpected finding, that the potential barrier for electron tunneling in the water-filled gaps is so high that a distance of 10 Å cannot be overcome. A more likely explanation is nonefficient energy transfer, which may be expected in nonorganized, aqueous systems. For experiments concerning charge separation between heterodimers, the bottom porphyrin will be converted to zinc- or tin(IV) complexes in order to function as donor or acceptor, and charged acceptor and donor molecules of the same size must be synthesized. The experimental findings on the properties of the yoctowells and its water-soluble blockers, extend the list of efficient blocking molecules by two neurotransmitters (dopamine, norepinephrine) and then report on attempts to quantify the amount of tyrosine which is quasi- irreversibly entrapped in the yoctowells on gold electrodes. Time dependent measurements of the radioactivity of 14C-labelled tyrosine proved the "insolubility" of the tyrosine which was entrapped within the well. Solid state 13C- and 1H-NMR spectroscopy on smooth silicate particles was applied to quantify the amount of tyrosine and water entrapped in the yoctowells. Infrared spectroscopy and proved the presence of D2O-dimers in the yoctowells. A "crust model" was then be introduced, which is in agreement with the observed stereochemical selectivities of the blocking agents in comparison to inactive compounds. It is known that zinc porphyrins form stable cation radicals, whereas free base porphyrins do not. For this purpose we had changed our bottom free base porphyrin 26b to zinc porphyrin 26c. The acceptor having same size of the bottom porphyrin which was successively synthesized from benzidine and anthraquinone sulfonate for this purpose we perform by Schiff base method bis-iminoquinone 36. Porphyrin-bis-iminoquinone heterodimers separated by a 5 Å, 10 Å and 15 Å defined distance was established on silica particles was confirmed by fluorescence quenching experiments. We applied these yocotwells with acceptor as a bis-iminoquinone for light induced charge transfer reaction applying again fluorescence decay measurement. A new, faster, and very efficient decay mechanism with a decay time of 0.12- 0.14 ns only appeared, when the bis-iminoquinone 36 was attached at a distance of 6 Å. When bis-iminoquinone 36 present at 10 Å and 15 Å we observed efficient decay mechanism is slowed down as compared to 5 Å, in the rang 0.15 ns for 10 Å and 0.18-0.19 ns for 15 Å. The electron transfer reaction seems to be distance independent, the electron travels perhaps along the hydrophobic walls like proton were shown to do. A time of 120-130 ps for 5 Å and 180 ps for 15 Å is in agreement with rates of electron transfers in the slowest literature model systems.Eine Reihe neuer Bolaamphiphile wurde synthetisiert, um Nanometer-weite Spalten in steifen Monoschichten auf aminierten Kieselgel Partikeln darzustellen. Diese Moleküle enthielten aktivierte C=C Doppelbindungen aus Horner-Wittig Reaktionen eines phosphorylierten Butylacetats mit 12-Formyldodecansäure oder 6-Oxo-hexansäure. Aus Tetraethoxysilan (TEOS) wurden durch Hydrolyse mit Ammoniak, Wasser und Äthanol kolloidale Silikatkügelchen hergestellt. Deren Oberfläche wurde mit 3-(Aminopropyl)-triäthoxysilan (APS) aminiert, wodurch die Partikel gegenüber Wasser und Lösungsmitteln stabilisiert und für die Anlagerung von Säurederivaten aktiviert wurden. Die Radien der Partikel waren vor allem von der Einwirkungszeit des Ammoniaks abhängig und lagen zwischen 20 und 150 nm. Die kleinen Partikel waren zu rau, um als Basis für den Membranaufbau benutzt zu werden, die kleinsten Teilchen mit einer vollkommen glatten Oberfläche hatten einen Radius von 100 ± 10 nm und wurden im Gramm-Maßstab hergestellt. Das m-Tetracarboxyporphyrin 26 wurde mit Chlorameisensäureäthylester zu 26b umgesetzt und in Form einzelner Moleküle auf das aminierte Kieselgel aufkondensiert. Domänenbildung wurde so vermieden. In einem zweiten self- assembly Schritt wurden dann die Bolaamphiphile 10 oder 16 aufgebracht. Die membranbedeckten Partikel wurden durch mehrfache Zentrifugation, Dispersion und Ultrabeschallung in Methylenchlorid gereinigt und gelöst. Bola 10 lieferte einen Abstand von 10 Å zwischen dem Bodenporphyrin und der aktivierten Doppelbindung, bei Bola 16 waren es 5 Å. Die Breite der Spalten lag einheitlich bei 22 Å. Die Bodenporphyrine und aufgelagerten Porphyrine waren sowohl UV/vis spektroskopisch als auch durch Fluoreszenz leicht nachweisbar. Die porösen Membranen wurden fluoreszenzspektroskopisch charakterisiert. Die Partikel mit und ohne Domänenbildung zeigten keinen messbaren Unterschied. Zugabe von Mn(III)TPPS löschte die Fluoreszenz in beiden Fällen vollständig. Die Bodenporphyrine wurden von passenden Mangan(III)- oder Cu(II)-Porphyrinaten innerhalb von etwa 30 Minuten erreicht, zu große Porphyrine drangen nicht ein. Wurde die Doppelbindung innerhalb der Pore durch Michael Addition von Methylamin aminiert (0.5 M), so zeigte auch das passende Mn(III)TPPS 27 keine Löscheffekte mehr. Negativ geladene Porphyrine wurden von dem Ammoniumring festgehalten, was sowohl durch UV/vis als auch Fluoreszenzspektren gezeigt werden konnte. Das zweite Porphyrin war nun in einem Abstand von 5 oder 10 Å parallel zum Bodenporphyrin fixiert, was den ersten präparativen Weg zu einem long-distance Heterodimeren eröffnet hat. Solche Systeme könnten zur Ladungstrennung mittels Sonnenlicht führen: 6 Å und 10 Å sind kurz genug, um einen Elektronentransfer vom angeregten Donor zum Akzeptor zu erlauben, und weit genug, um die spontane Vereinigung der getrennten Ladungen sehr langsam zu machen. Außerdem ist es leicht möglich, ausgeblichene Außenmoleküle durch pH-Änderungen auszutauschen. Versuche zur Ladungstrennung mittels Blitzlichtphotolyse werden so zu Routinemessungen, wobei lediglich die sehr geringe Konzentration der Redoxpartner in den Monoschichten stört. Mangan(III) Porphyrine in 5 Å Abstand zeigten einen 0.16 ns Abfall, in 10 Å Abstand hatte es keinen Effekt. Eine weitere Abklingzeit von 160 ps deutet auf einen langsamen Elektronentransfer, welcher in der Literatur in Acetonitril nachgewiesen wurde. 10 Å mag in Wasser mit hoher Solvationsenergie zu weit für einen Elektronentransport sein. Experimente mit photochemischem Zinn(IV) und Zn Porphyrinaten konnten noch nicht abgeschlossen werden. Außerdem wurden die Kenntnisse über die Blockierung von Yoktobrunnen mit steifen Kantenamphiphilen erweitert und ein experimentell belegtes Modell entwickelt. Tryptamin blockierte sie vollständig für den Transport von Fe (CN)63--Ionen, wenn die Goldelektrode mit Monoschicht und Yoctobrunnen mit einer 0.1 M Lösung dieser Verbindungen über Nacht behandelt wurde. Zeitabhängige Messungen der Radioaktivität von 14C-Tyrosin in den Brunnen, die in Kontakt mit Volumenwasser gebracht wurden, bewiesen die "Unlöslichkeit" der im Yoctobrunnen absorbierten Moleküle im Volumenwasser, das in direktem Kontakt mit ihnen war. 13C- und 1H-NMR Spektroskopie der Silikat-Partikel mit eingeschlossenem Tyrosin zeigte ebenfalls die Unbeweglichkeit des eingschlossenen Tyrosins und Wassers. Infrarot-Spektroskopie wies auf D2O- Dimere. Diese Ergebnisse führten zur Formulierung eines Krustenmodells des Tyrosins auf die Oberfläche der hydrophoben Membran, das in Übereinstimmung mit allen Messungen und Strukturbefunden ist. Schließlich ersetzten wir die freie Base des Bodenporphyrins 26b im long-distance Dimer des Silikat- Yoctobrunnensystems durch einen redoxaktiven Zinkkomplex 26c. Als Akzeptor wurde das genau in den Brunnen passende Imino-dichinon 36 benutzt und in 6, 10 und 15 Å Abstand vom Boden Zinkporphyrinat fixiert. Die Fluoreszenz- Abklingkurven zeigten einen 0.12�0.14 ns Abfall bei einem Porphyrin-Chinon Abstand von 5 Å, von 0.15 ns bei 10 Å und 0.18�0.19 ns bei 19 Å Abstand. Diese Unterschiede sind sehr gering. Vielleicht wandert das Elektron entlang den hydrophoben Wänden, so wie es bei Protonen gezeigt wurde. Die langsamen Zeiten von 120 ps für 6 Å und 180 ps für 15 Å sind eher in Übereinstimmung mit Literaturwerten. Die vorläufigen Messungen zur Ladungstrennung müssen weitergeführt und noch eindeutig analysiert und eingeordnet werden

Fluorescence Probes for Sensing

The rapid progress in sensor science in recent years has resulted in the development of fluorescence probes with enhanced analytical capabilities. Because of the vast evolution of this research field, therefore, we have decided to combine all the research articles published in "Fluorescence Probes and Sensors" for a Special Issue (SI) book of Sensors which was focusing on the important role sensors play in “Fluorescent Probes and Sensors”. Fluorescence novel Probes make an ideal candidate for promising applications in biological analytes and environmental monitoring. Fluorescent probes along with metal complexes have been developed as a new class of fluorophores with excellent properties. This book illustrating the suitability of newly developed sensors for fluorescent analysis applications, as well as describing novel applications of established sensors in solving real life analytical problems

A Simple Method to Identify Supramolecules in Action: Hill Coefficients for Exergonic Self-Assembly

Precise supramolecular architecture is often essential for significant function. Simple methods to reliably and rapidly demonstrate the existence of such supramolecular structure and function at relevant concentrations in complex systems are badly needed. Hill plots, describing the dependence of a signal on the n-th power of the monomer concentration, are compatible only with the identification of supramolecules that do not really exist, that is, endergonic self-assembly (Litvinchuk et al., J Am Chem Soc 2004;126:10067). Here, we show that the artificial increase in monomer concentration by chemical denaturation restores compatibility of Hill plots with exergonic self-assembly and affords Hill coefficients n > 1 for stable supramolecules. Recent rigid-rod pi-stack architecture with photosynthetic and ion channel activity is used as timely example, circular dichroism (CD) spectroscopy as method of choice for both sensitive and selective detection under relevant conditions

Tetraphosphonic acid functionalized perylenediimide derivative: Synthesis and pH dependent photophysical properties

693-696The synthesis of phosphonic acid functionalized perylene diimide (PDI) molecular architecture has been demonstrated via functionalization at imide position. UV-Vis absorption and fluorescence emission spectroscopic techniques have been employed to investigate the photophysical properties of the novel PDI derivative at different pH (2 to 11). These results demonstrate the fascinating photophysical characteristics based on change in pH from 7 to 2 and 7 to 11 in aqueous medium