Showing papers by "Edamana Prasad published in 2018"
TL;DR: In this paper, the authors presented a novel, well-defined and highly structured crystalline π-conjugated nanowall framework, called pyrediyne (pyrene + diyne = pyredyne), with large inplane periodicity.
Abstract: Synthesizing graphdiyne analogues with a well-defined structure and desirable band gap is a challenging task. Herein, we present a novel, well-defined and highly structured crystalline π-conjugated nanowall framework, called pyrediyne (pyrene + diyne = pyrediyne), with large in-plane periodicity. The bulk synthesis of the two-dimensional (2D) ultrathin polymeric framework of pyrediyne is achieved via a modified-Glaser–Hay coupling reaction using 1,3,6,8-tetraethynylpyrene. The ultrathin π-conjugated crystalline pyrediyne nanowall is well characterized by Raman, SEM, AFM, HR-TEM and XPS techniques. Electronic structure information reveals the π-conjugated framework to be completely planar with a Cs point group, where a tunable band gap of Eg ∼ 1.17 eV can be achieved depending on the number of pyrene units. The electrostatic potential maps reveal complete π-delocalization of the electron cloud throughout the framework with a high electronegative potential at the acetylenic linkages. This through-bond charge coupling via the conjugated network in conjunction with the charge delocalization via the π⋯π interactions in space accounts for the significant electrical conductivity {σ = 1.23(±0.1) × 10−3 S m−1} of the organic material.
24 citations
TL;DR: An electroactive supergelator (c=0.07 wt %) triphenylamine core-appended poly(aryl ether) dendron (TPAPAE) is described, where substantial dendritic effects improve the order and crystallinity by switching the local minima from self-assembled molecular wires to thermodynamically favorable global minima of ordered crystals.
Abstract: Smart single-component materials with versatile functions require pre-programming of a higher order molecular assembly. An electroactive supergelator (c=0.07 wt %) triphenylamine core-appended poly(aryl ether) dendron (TPAPAE) is described, where substantial dendritic effects improve the order and crystallinity by switching the local minima from self-assembled molecular wires to thermodynamically favorable global minima of ordered crystals, ripened within the fibers. Controlled in situ phase change at room temperature ultimately stabilized the mixed valence states in the single-component supramolecular assembly with photoluminescence and photoinduced charge transport amplified by two orders of magnitude.
15 citations
13 citations
TL;DR: Two distinct molecular designs based on phenothiazine as a donor and triarylborane and cyanostilbene as acceptors are reported, for example, an acceptor–donor–acceptor system (A–D–A; compound 3) and donor– acceptor (D– A; compound 4) moieties, in which 3 exhibits polymorphism with two distinct emissions.
Abstract: Organic π-conjugated compounds showing polymorphic and mechanofluorochromic (MFC) behaviors are promising candidates for many potential applications in materials chemistry. Herein, we report two distinct molecular designs based on phenothiazine as a donor and triarylborane and cyanostilbene as acceptors, for example, an acceptor–donor–acceptor system (A–D–A; compound 3) and donor–acceptor (D–A; compound 4) moieties, in which 3 exhibits polymorphism with two distinct emissions (yellow and red). The single crystal X-ray diffraction analyses of 3 clearly show two conformational isomers. The color of the emission can be altered by a grinding or fuming process.
12 citations
TL;DR: In this article, the influence of the solvent (dielectric constant) on the digestive ripening of copper oxide quantum dots was explored, where water, ethylene glycol, methanol, ethanol, propanol, butanol, and pentanol were chosen as solvents.
10 citations
TL;DR: In this article, the origin of nano-galvanic couple formation on in-situ formed nano-aluminum amalgam surfaces in a water splitting system was investigated using high resolution Scanning Kelvin Probe Force Microscopy (SKPFM).
7 citations
TL;DR: In this paper, the diffusion-controlled back electron transfer (BET) from GQD radical anion to DEA radical cation is diffusion controlled, and an analytical expression for the diffusion control rate constant has been formulated.
Abstract: In the present study, the stability of the photogenerated, solvent-separated charged states of graphene quantum dots (GQDs) in the presence of N,N-diethylaniline (DEA) has been evaluated in a series of organic solvents. The results indicate that the rate constant for back electron transfer (kBET) from GQD radical anion to DEA radical cation is diffusion-controlled. As a result of the diffusion-controlled back electron transfer (BET), kBET exhibits an inverse exponential relation to (a) the viscosity coefficient (η) of the solvent and (b) the average radius of the graphene quantum dots. An analytical expression for the diffusion-controlled back electron transfer rate constant has been formulated. The dependence of kBET on the diffusion of solvent-separated ion pairs has been evaluated for the first time for quantum dot systems and the results provide an efficient method for enhancing the lifetime of the photogenerated charge-separated states from graphene quantum dots. The present findings can potentially ...
5 citations
TL;DR: In this article, photo-induced electron transfer (PET) dynamics between N,N-diethylaniline (DEA) and (E)-9-(4-nitrostyryl)anthracene (An-NO) was investigated.
Abstract: In the present study, photoinduced electron transfer (PET) dynamics between N,N-diethylaniline (DEA) and (E)-9-(4-nitrostyryl)anthracene (
$$\hbox {An-NO}_{2}$$
) in a non-polar solvent medium {methylcyclohexane (MCH)}, has been investigated. The rate constant of back electron transfer (
$$\hbox {k}_{{\mathrm{BET}}}$$
) for the $$\hbox {An-NO}_{2}$$
– DEA pair was $$\sim 3.8\times 10^{5}~\hbox {s}^{-1}$$
which is ca. 2 orders of magnitude less compared to the anthracene (An)-DEA (control) system. The results indicate that long-lived charge separated species can be generated using the design strategy used herein by achieving resonance stabilization of the excited state (acceptor) radical via conjugation. SYNOPSIS For N,N-diethylaniline/(E)-9-(4-nitrostyryl)anthracene donor-acceptor pair, the back electron transfer rate constant is $$\sim 2$$
orders of magnitude slower compared to N,N-diethylaniline/anthracene system. The results indicate that organic molecules with extended $$\uppi $$
-conjugation can be utilized for generating long-lived charge separated states via bimolecular PET, due to increased feasibility of charge delocalization.
4 citations
TL;DR: The degree of ICT and the gelation abilities of OPVs were significantly influenced by the electronic nature of the substituents appended to the peripheral phenothiazines, and the AC impedance results revealed an increase in storage and electronic transport for the fluorescent thin films prepared by a increase in the content of OPV4 in PMMA.
Abstract: Designing intramolecular charge-transfer (ICT)-based luminogenic ordered assemblies exhibiting significant electrical transport is a challenging task in the field of organic optoelectronics. In this context, a series of novel phenothiazine-based oligo(p-phenylenevinylene) (OPV1-6) derivatives were designed and their structure-property relationship was investigated. Upon examining their photophysical properties, all the OPVs were found to exhibit significant intramolecular charge-transfer characteristics in organic solvents. While inspecting the self-assembly behaviour, the OPV with a long alkyl chain on the central phenyl core (OPV4) underwent gelation in organic solvent mixtures through strong hydrophobic interactions of the long hexadecyl chains and π-interactions from their aromatic counterparts. Computational studies revealed a lamellar packing of molecules in the assembly. Interestingly, the degree of ICT and the gelation abilities of OPVs were significantly influenced by the electronic nature of the substituents appended to the peripheral phenothiazines. Further, the AC impedance results revealed an increase in storage and electronic transport for the fluorescent thin films prepared by an increase in the content of OPV4 in PMMA.
3 citations
TL;DR: Photophysical study revealed that these π-extended imidazoquinolines display large Stokes shifts (up to 158 nm) and high fluorescent quantum yields.
Abstract: Bronsted acid-promoted straightforward synthesis of N-fused tricyclic angular imidazoquinolines in high yields is realized through a succinct 1,3-hydride shift. The protocol is operationally simple, scalable, and features broad scope. A photophysical study revealed that these π-extended imidazoquinolines display large Stokes shifts (up to 158 nm) and high fluorescent quantum yields.