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.

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

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

Thiophene functionalized naphthalene diimide for the sensitive detection of nitroaromatics

696-702In recent years, the detection of nitroaromatics (NACs) has attracted the researchers’ attention due to increased threats of terrorist and environmental protection. In this regard, tetra-thiophene (Th) functionalized naphthalene diimide (NDI) conjugate NDI-Th has been synthesized and confirmed via spectroscopic methods. UV-Vis and fluorescence methods have been utilized to examine the photophysical characteristics of NDI-Th in various solvent systems. Moreover, NDI-Th as a fluorescent sensor displays selective recognition of 2,4-dinitrophenol (DNP) and 2,4-trinitrophenol (TNP) with a limit of detection of 4.74×10–8 M and 7.60×10–8 M, respectively. Thus NDI-Th acts as a promising candidate for explosive multi-NACs detection

Triphenylamine-Merocyanine-Based D1-A1-π-A2/A3-D2 Chromophore System: Synthesis, Optoelectronic, and Theoretical Studies

donor–acceptorDonor–acceptor–π–acceptor–donor (D1-A1-π-A2/A3-D2)-type small molecules, such TPA-MC-2 and TPA-MC-3, were designed and synthesized starting from donor-substituted alkynes (TPA-MC-1) via [2 + 2] cycloaddition−retroelectrocyclization reaction with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) units, respectively. TPA-MC-2 and TPA-MC-3 chromophores differ on the A2/A3 acceptor subunit, which is 1,1,4,4-tetracyanobutadiene (TCBD) and a dicyanoquinodicyanomethane (DCQDCM), respectively. Both the derivative bearing same donors D1 (triphenylamine) and D2 (trimethylindolinm) and also same A1 (monocyano) as an acceptor, tetracyano with an aryl rings as the π-bridging moiety. The incorporation of TCNE and TCNQ as strong electron withdrawing units led to strong intramolecular charge-transfer (ICT) interactions, resulting in lower LUMO energy levels. Comparative UV–Vis absorption, fluorescence emission, and electrochemical and computational studies were performed to understand the effects of the TCNE and TCNQ subunits incorporated on TPA-MC-2 and TPA-MC-3, respectively

Efficient symmetric supercapacitors employing molecular engineered pyrazine functionalized perylene diimide electrode materials

Redox active small organic molecules (OM) are the promising materials for energy storage applications. The practical utilization of such materials in combination with excellent redox-active material is advantageous to enhance the specific capacitance (Csp). Herein, naphthalene diimide (NDI) and perylenediimide (PDI) molecules linked with pyrazine (Pyr) are exploited as faradiac reversible redox-active material on graphite foil (GF) surface to act as electrode materials in supercapacitor (SC) device. The as-fabricated NDI-Pyr/GF and PDI-Pyr/GF electrodes were optimized in three-electrode SC device in view of their electrochemical performance. The NDI-Pyr/GF and PDI-Pyr/GF in SC device demonstrated a Csp of about 260 and 302 F g−1, respectively at 0.5 A g−1 current density. However, in two-electrode symmetric supercapacitor (SSC) device i.e. PDI-Pyr/GF//PDI-Pyr/GF exhibited excellent Csp of about 192 F g−1 at 1 A g−1 current density with longer cycling stability with 88.13% after 4000 galvanostatic (GCD) charge/discharge cycles. Furthermore, an excellent energy density of 54 Wh kg−1 at a power density of 2700 W kg−1 is provided by the SSC device. These results suggest that the as-prepared PDI-Pyr/GF//PDI-Pyr/GF have practical energy storage application in OSC devices

Pyrene-Phosphonate Conjugate: Aggregation-Induced Enhanced Emission, and Selective Fe3+ Ions Sensing Properties

A new pyrene-phosphonate colorimetric receptor 1 has been designed and synthesized in a one-step process via amide bond formation between pyrene butyric acid chloride and phosphonate-appended aniline. The pyrene-phosphonate receptor 1 showed aggregation-induced enhanced emission (AIEE) properties in water/acetonitrile (ACN) solutions. Dynamic light scattering (DLS) characterization revealed that the aggregates of receptor 1 at 80% water fraction have an average size of ≈142 nm. Field emission scanning electron microscopy (FE-SEM) analysis confirmed the formation of spherical aggregates upon solvent evaporation. The sensing properties of receptor 1 were investigated by UV-vis, fluorescence emission spectroscopy, and other optical methods. Among the tested metal ions, receptor 1 is capable of recognizing the Fe3+ ion selectively. The changes in spectral measurements were explained on the basis of complex formation. The composition of receptor 1 and Fe3+ ions was determined by using Job’s plot and found to be 1:1. The receptor 1–Fe3+ complex showed a reversible UV-vis response in the presence of EDTA

Design and synthesis of phosphonate functionalized naphthalenediimide: Application to induce mitochondria mediated apoptosis in the human skin melanoma cells (SKMEL2)

506-512New phosphonate functionalized naphthalenediimides (NDI-1 and NDI-2) have been synthesized and evaluated as potential drug candidates to treat the skin malignancy. The aforementioned candidates have resulted in an induced apoptosis pathway of cytotoxicity, at concentrations lower than 4 μM, in human skin melanoma cells, and elicited a stronger apoptotic response in cells. Regulation of the Bcl2, Caspases, Bak1, Bax protein in NDI-induced apoptosis in cells has been analyzed by real time PCR, and the cell viability and apoptosis determined by flow cytometry. The obtained results indicate that NDIinduced apoptosis by regulation of Bcl2 and Bak1 occurs in human skin melanoma cells (SKMEL-2)