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Leishmania donovani are intracellular, human blood parasites that cause visceral leishmaniasis or kala-azar. Cell-penetrating peptides (CPPs) have been shown to modulate intracellular processes and cargo delivery, whereas host defense peptides (HDPs) promote proliferation of both naïve and antigen activated CD4+ T-cells. We report newly designed tripeptides that were able to trigger proinflammatory cytokine (IL-12 and IFN-γ) secretion by CD4+CD44+ T-cells in response to Leishmania donovani infection. These peptides can be used to induce antigen specific TH1 responses to combat obstacles of cytotoxicity and drug resistance associated with current anti-leishmanial drugs. Furthermore, these peptides can also be used as adjuvants to develop an effective immunoprophylactic approach for immunity restoration against visceral leishmaniasis. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) holds promise as a cytotoxic agent against tumors, but its gaseous nature and short half-life hinder direct administration to tumor tissues. Herein, we present novel 6,9-disubstituted purine derivatives designed to ensure sustained NO release, followed by study of their significant anti-proliferative, anti-migratory, and anti-clonogenic effects on HepG2 cell lines, highlighting NO release as a potent effector for treating hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]

Topological insulators have emerged as one of the most promising candidates for the fabrication of novel electronic and optoelectronic devices due to the unique properties of nontrivial Dirac cones on the surface and a narrow bandgap in the bulk. In this work, the Sb2Te3 and Bi2Te2Se materials, and their heterostructure are fabricated by metal–organic chemical vapour deposition and evaporation techniques. Photodetection of these materials and their heterostructure shows that they detect light in a broadband range of 600 to 1100 nm with maximum photoresponse of Sb2Te3, Bi2Te2Se and Sb2Te3/Bi2Te2Se at 1100, 1000, and 1000 nm, respectively. The maximum responsivity values of Sb2Te3, Bi2Te2Se, and their heterostructure are 183, 341.8, and 245.9 A W−1 at 1000 nm, respectively. A computational study has also been done using density functional theory (DFT). Using the first-principles methods based on DFT, we have systematically investigated these topological insulators and their heterostructure's electronic and optical properties. The band structures of Sb2Te3 and Bi2Te2Se thin films (3 QL) and their heterostructure are calculated. The bandgaps of Sb2Te3 and Bi2Te2Se are 26.4 and 23 meV, respectively, while the Sb2Te3/Bi2Te2Se heterostructure shows metallic behaviour. For the optical properties, the dielectric function's real and imaginary parts are calculated using DFT and random phase approximation (RPA). It is observed that these topological materials and their heterostructure are light absorbers in a broadband range, with maximum absorption at 1.90, 2.40, and 3.21 eV. [ABSTRACT FROM AUTHOR]

Bioactive molecules that enhance or induce osteogenic potential of bone precursor cells have shown vital roles in bone tissue engineering. Herein, we report the design and synthesis of a novel diketopiperazine (DT) that induces osteoblastic differentiation of pre-osteoblasts and bone-marrow-derived stem cells in vitro and enhances the osteogenic potential of cryogel matrix. Such functional diketopiperazines can serve as potential scaffolds for bone healing and regeneration. [ABSTRACT FROM AUTHOR]

Incorporation of fluorescent α-amino acids in peptide/protein sequences, at desired positions, is eminently useful for non-invasive detection of cellular events, without impacting their native properties. As an extension to such an approach, we describe the design of two stable, fluorescent L -tyrosine analogs, FHBY and BHBY, exhibiting photophysical properties associated with the AIE-coupled ESIPT mechanism, for fluorescent reporting of latent fingerprints. Notably, FHBY selectively adheres to the papillary ridges of latent fingerprints and reveals up to the third-level of information at one of the lowest reported concentrations of 25 μM. [ABSTRACT FROM AUTHOR]

Inspired by natural metallopeptides, we have rationally designed two pyridine-conjugated short peptides. These two peptide conjugates formed a pair of constitutional isomers that helped us describe their structure–function relationship. Both the isomers consisted of an equal number of aromatic amino acid residues, but shuffling was observed in the position of two key amino acids, viz; tyrosine and phenylalanine, which brought a remarkable change in their self-assembling behavior. The presence of specific functional groups and chemical diversity in both conjugates made them very active towards metal coordination. Both the constitutional isomers adopted different pathways of self-assembly, which could be further controlled or transformed by the use of transition metal ions. Interestingly, it was observed that the metal ions could precisely control the morphology of these metallopeptide nanostructures and make them more stable. Therefore, such artificial metallopeptides possess remarkable advantages over the natural counterparts primarily due to their tailor-made chemical structures. [ABSTRACT FROM AUTHOR]

Phenol–metal coordination polymers are used in applications such as catalysis, sensing and separation science. In addition, combining eco-friendly conditions with economical and handling advantages of the polymeric catalyst is of interest to the community. Here, we report a simple one pot synthesis of a tetracatechol based ligand and its coordination polymer with copper ions. The Cu polymer showed electrochemical potential with a band gap of 1.01 eV. The BET surface area of the metallopolymer was 91.19 m2 g−1 with 0.14 cm3 g−1 pore volume. The polymer catalyst was used in a one pot three component click reaction and in the borylation of unsaturated carbonyl compounds with a maximum 99% conversion in water and good turnover efficiency even after 4 repetitive catalysis cycles. The polymer catalyst offers several advantages such as high activity, easy handling, scalability, recyclability and cost effectiveness. [ABSTRACT FROM AUTHOR]

Nontoxic adhesive hydrogels are of great importance in tissue engineering. Herein, we report a simple synthesis of a few biocompatible hydrogels from adenine and dopamine immobilized polyacrylic acid (PAA) and alginic acid (Alg) polymers. The adenine–dopamine adduct incorporated hydrogels showed enhanced adhesiveness, transparency and biocompatibility, and induced cell proliferation in 2D and 3D-cell culture models within 24 h. Moreover, blending the modified PAA and Alg polymers (P2P4) further increased the stability and bioactivity of the hydrogel. Such biogels can be developed as smart materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Flexible and free-standing polymeric fibers, coupled with metal nanoparticles, present an excellent opportunity for highly sensitive surface-enhanced Raman scattering (SERS) spectroscopy-based detection platforms. Such host matrices are prepared by only a few preferred methods, followed by induction of metal nanoparticle aggregation in a protected environment to afford functional SERS platforms. We provide an interesting advance in this area by choosing a thiol-modified purine (L)–polymer blend, obtained through the electrospinning process, for directed decoration with gold nanoparticles. The described SERS purine-nanomat substrate enables the detection of uric acid, an important indicator of gout, preeclampsia, cardiovascular and kidney diseases, in aqueous solution up to 100 nM, with good stability and high sensitivity, offering superiority over existing techniques in terms of sensitivity and cost-effectiveness. [ABSTRACT FROM AUTHOR]

We demonstrate the ability of two tripeptides to promote proliferation and modulate the mechanical properties of human mesenchymal stem cells (hMSCs). Notably, Young's modulus of peptide-treated hMSCs was found to be ∼2 fold higher compared to the control group. These peptides promoted wound healing in hMSCs, without stimulating osteogenic and adipogenic differentiation, thus showing high potential in vascular tissue engineering applications. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide, an endogenous signalling molecule, is central to several pathophysiological processes in mammalian systems. It scavenges reactive oxygen species and is known to ameliorate dopaminergic neuronal degeneration in neurotoxin-induced Parkinson's disease models. The rapid volatilization of H2S from spontaneously releasing sulfide salts being a challenge, we describe peptide conjugates which exhibit tris(2-carboxyethyl)phosphine mediated "slow and sustained" H2S release. These conjugates reduced hydrogen peroxide-induced oxidative stress and significantly increased dopamine levels in transgenic C. elegans. [ABSTRACT FROM AUTHOR]

Nosocomial infections arising from opportunistic pathogens, such as Staphylococcus aureus, are growing unabated, compounded by the rapid emergence of antimicrobial resistance. Herein, we demonstrate a new molecular design that exhibits excellent activity against multidrug-resistant S. aureus with no cytotoxicity and resensitizes fluoroquinolones (FQ) towards FQ-resistant methicillin-resistant S. aureus strains, with DNA gyrase B as the likely molecular target as determined by molecular dynamics (MD) simulations. [ABSTRACT FROM AUTHOR]

Semiconductor heterostructures with type-II band alignment are well known for their engineering property of efficient charge separation in photogenerated carriers. Herein, type-II CdSe/ZnO core/shell quantum dot heterostructures with CdSe shells of different thicknesses have been synthesized and a study of carrier dynamics is carried out using femtosecond transient absorption and picosecond emission spectroscopy. Carrier lifetime measurements by transient emission spectroscopy have revealed reduced electron–hole overlap in the type-II localization regime of ZnO/CdSe heterostructures. Femtosecond transient absorption studies have revealed hot electron transfer from CdSe shell to ZnO core prior to electron cooling in the CdSe shell. In addition, a surface channel for the hole cooling process has been identified in the transient absorption measurements. Effects of carrier trapping at interfacial defect states and type-II localization on carrier recombination have been recognized in our transient absorption and emission studies of ZnO/CdSe QDs heterostructure. [ABSTRACT FROM AUTHOR]

We present a series of six copper(ii) complexes with N9-modified 6-chloropurines to investigate their mode of binding, dimensionality and the role of non-covalent interactions in structure stabilisation. Four strategically designed and synthesised ligands interacted with Cu(ii) to afford complexes possessing novel structural features. These complexes possessing divergent lattice structures were characterised and discussed thoroughly, and the prospect of their use as thin film precursors was explored through the preparation of copper oxide thin films by a chemical vapour deposition (CVD) method on quartz and Si(111) substrates. [ABSTRACT FROM AUTHOR]

In this feature article, targeted design strategies are outlined for modified adenine nucleobase derivatives in order to construct metal-mediated discrete complexes, ring-expanded purine skeletons, linear and catenated coordination polymers, shape-selective MOFs, and purine-capped nanoparticles, with a wide range of applications from gas and solvent adsorption to bioimaging agents and anticancer metallodrugs. The success of such design strategies could be ascribed to the rich chemistry of purine and pyrimidine derivatives, versatile coordination behavior, ability to bind a host of metal ions, which could be further tuned by the introduction of additional functionalities, and their inherent propensity to hydrogen bond and exhibit π–π interactions. These noncovalent interactions produce stable frameworks and network solids that are useful as advanced materials, and the biocompatibility of these ligand complexes provides an impetus for assessing novel biological applications. [ABSTRACT FROM AUTHOR]

The reaction of L1H {L1H = 3-(N9-guaninyl)propionic acid} with Me3SnCl or (n-Bu3Sn)2O afforded the 1D coordination polymers, [Me3Sn(L1)]n (1) and [n-Bu3Sn(L1)]n (2) respectively. A reaction between L2H {L2H = 3-(N7-guaninyl)propionic acid} with Me3SnCl also afforded a 1D coordination polymer, [Me3Sn(L2)]n (3). A similar reaction between L3H [uracil-6-carboxylic acid] with (Ph3Sn)2O in a 2 : 1 ratio afforded a dimer [(n-Bu3SnL3)2·H2O] (4). A mononuclear compound [Me3Sn(L4)·H2O] (5) was obtained in a 1 : 1 reaction of 3-{N9-(2-aminopurinyl)}propanoic acid (L4H) with Me3SnCl. Complexes 1–5 show rich supramolecular structures in the solid state as a result of several intermolecular interactions. Thus, in the one-dimensional coordination polymer 3, triple hydrogen bonding (G≡G), between inter-chain guanine units has been observed. Similarly a homo orotatequartet has been observed in 4 as a result of intermolecular interactions. [ABSTRACT FROM AUTHOR]

A new in vitro assay was developed to detect human epidermal growth factor receptor 2 (HER2) protein, based on affinity dissociation of carbon nanotube (CNT)-wrapped anti-HER2 ssDNA aptamers. First, we selected an anti-HER2 ssDNA aptamer (H2) using an in vitro serial evolution of ligands by an exponential enrichment (SELEX) process. Then the fluorescently labelled H2 ssDNAs were tightly packed on CNTs that had previously been coupled with magnetic microbeads (MBs), forming MB-CNT-H2 hybrids. The loading capacity of these MB-CNTs heterostructures (2.8 x 108) was determined to be 0.025 to 3.125 μM of H2. HER2 protein-induced H2 dissociation occurred from MB-CNT-H2 hybrids, which was specifically induced by the target HER2 protein, with a dissociation constant (Kd) of 270 nM. The stoichiometric affinity dissociation ratio with respect to H2-to-HER2 protein was shown to be approximately 1 : 1. Our results demonstrated that the developed assay can be an effective approach in detecting native forms of disease biomarkers in free solutions or in biological samples, for accurate diagnosis. [ABSTRACT FROM AUTHOR]

Enzyme modifiable, hollow self-assembled structures offer an excellent scope for multiantennary delivery vectors. Herein, we report synthesis and applications of bis-galactose lysine based supramolecular ensembles, which possess surface galactose moieties amenable to enzymatic modifications. This post-synthetic modification generates reactive aldehyde groups, which could possibly serve as dynamic anchors for crosslinking and cell adhesion. [ABSTRACT FROM AUTHOR]

Cadmium, a metal known to be toxic to living systems through unfavorable interactions with biomolecules, interacts with purine nucleobases through N7 imino nitrogen and induces modifications by altering amino--imino tautomeric equilibrium. Herein, we report unique crystallographic signatures of cadmium complexes of N9-benzyl-N6-methoxyadenine, a rare imino tautomer of adenine. These complexes exhibit a variety of coordination numbers and spatial geometries, highlighting the ability of nucleobases to form diverse supramolecular architectures, enabling better understanding of metal--DNA interactions. The Cd2+ ion in complex 1 has a coordination number of four with a distorted tetrahedral geometry, while 2 and 3 are hexa-coordinated, where 2 displays a discrete distorted octahedron geometry and 3 appears as a dinuclear complex. On the other hand, complex 4 exhibits a less common hepta-coordination mode with a distorted pentagonal bipyramidal geometry. The luminescence properties of these cadmium complexes are also reported. [ABSTRACT FROM AUTHOR]

This communication describes the synthesis, structural investigation and tubulin binding of purine rare imino-tautomer based Ag(I) and Hg(II)-carbene complexes. These complexes exhibit cytotoxicity through tubulin interaction by binding to a site close to the GTP binding site. [ABSTRACT FROM AUTHOR]

Three copper-N9-modified guanine complexes are reported with structures ranging from a discrete trinuclear motif to a mixed-valence coordination polymer. These complexes were used as precursors for the deposition and growth of copper oxide thin films on Si(100), at two different annealing temperatures, by using a CVD technique. Subsequent resistivity measurements suggest the formation of conductive thin films, raising the possibility of using nucleobase-metal complexes as versatile thin film precursors. [ABSTRACT FROM AUTHOR]

Crystallographic investigations of N9-propyladenine N1-oxide silver complexes, having different counteranions, are reported. While hydrogen bonded 1D polymeric chains were observed in case of NO3− (1) and BF4− (2); PF6− (3) and OTf− (4) afforded six membered metallacycles; and ClO4− (5) resulted in coordination polymers comprising of quartet of dimeric assemblies. [ABSTRACT FROM AUTHOR]

We have synthesized ruthenium(ii) polypyridyl complexes (1) Ru(ii)(bpy)2(L1), (2) Ru(ii)(bpy)2(L2) and (3) Ru(ii)(bpy)(L1)(L2), where bpy = 2,2′-bipyridyl, L1= 4-[2-(4′-methyl-2,2′-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) and L2= 4-(N,N-dimethylamino-phenyl)-(2,2′-bipyridine) and investigated the intra-ligand charge transfer (ILCT) and ligand–ligand charge transfer (LLCT) states by optical absorption and emission studies. Our studies show that the presence of electron donating –NMe2functionality in L2and electron withdrawing catechol fragment in L1ligands of complex 3introduces low energy LLCT excited states to aboriginal MLCT states. The superimposed LLCT and MLCT state produces redshift and broadening in the optical absorption spectra of complex 3in comparison to complexes 1and 2. The emission quantum yield of complex 3is observed to be extremely low in comparison to that of complex 1and 2at room temperature. This is attributed to quenching of the 3MLCT state by the low-emissive 3LLCT state. The emission due to ligand localized CT state (ILCT and LLCT) of complexes 2and 3is revealed at 77 K in the form of a new luminescence band which appeared in the 670–760 nm region. The LLCT excited state of complex 3is populated either viadirect photoexcitation in the LLCT absorption band (350–700 nm) or through internal conversion from the photoexcited 3MLCT (400–600 nm) states. The internal conversion rate is determined by quenching of the 3MLCT state in a time resolved emission study. The internal conversion to LLCT and ILCT excited states are observed to be as fast as ∼200 ps and ∼700 ps for complexes 3and 2, respectively. The present study illustrates the photophysical property of the ligand localized excited state of newly synthesized heteroleptic ruthenium(ii) polypyridyl complexes. [ABSTRACT FROM AUTHOR]

The grafting of a short nucleic acid strand to ditryptophan dipeptide (WW) results in a peptide-DNA hybrid, which assembles into fibrils under controlled aggregation conditions as evidenced by label free optical sensing owing to the intrinsic fluorescence of the dipeptide. [ABSTRACT FROM AUTHOR]

This communication describes mercury(ii)-mediated cyclization of N9-propargylguanine under hydrothermal conditions. The structural investigations reported here confirm cyclization and reveal simultaneous formation of a unique organomercury adduct of a tricyclic guanine derivative. [ABSTRACT FROM AUTHOR]

The assembly of double-stranded (ds) DNA nanocircles both by hybridization with branched oligodeoxynucleotides (ODNs) and by intercalation was analyzed by atomic force microscopy (AFM). Branched ODNs ligated to single-stranded (ss) gap regions of dsDNA nanocircles led to defined, dumbbell-shaped architectures. ODNs containing an aromatic intercalator yielded oligomeric aggregates. [ABSTRACT FROM AUTHOR]

The binding of biotin to human erythrocytes (red blood cells, RBCs) is followed with the help of optical and atomic force microscopy methods. As certain biotin derivatives gain access to Plasmodium falciparuminfected erythrocytes and block parasite-induced transport of other solutes, the microscopy observations reported in this communication will provide impetus to unravel the access mechanism of biotin and its derivatives to malaria infected erythrocytes. [ABSTRACT FROM AUTHOR]

We report the formation of a highly unusual fused, tricyclic purine derivative viaN3 alkylation of 9-propargyladenine, upon activation of the acetylenic triple bond by Ag(i) ions. The participation of silver ions in this process might offer newer design paradigms for minor groove N3 DNA alkylation, antibacterial and anticancer agents. [ABSTRACT FROM AUTHOR]

Leishmania donovani are intracellular, human blood parasites that cause visceral leishmaniasis or kala-azar. Cell-penetrating peptides (CPPs) have been shown to modulate intracellular processes and cargo delivery, whereas host defense peptides (HDPs) promote proliferation of both naïve and antigen activated CD4 + T-cells. We report newly designed tripeptides that were able to trigger proinflammatory cytokine (IL-12 and IFN-γ) secretion by CD4 + CD44 + T-cells in response to Leishmania donovani infection. These peptides can be used to induce antigen specific T H 1 responses to combat obstacles of cytotoxicity and drug resistance associated with current anti-leishmanial drugs. Furthermore, these peptides can also be used as adjuvants to develop an effective immunoprophylactic approach for immunity restoration against visceral leishmaniasis.

Topological insulators have emerged as one of the most promising candidates for the fabrication of novel electronic and optoelectronic devices due to the unique properties of nontrivial Dirac cones on the surface and a narrow bandgap in the bulk. In this work, the Sb 2 Te 3 and Bi 2 Te 2 Se materials, and their heterostructure are fabricated by metal-organic chemical vapour deposition and evaporation techniques. Photodetection of these materials and their heterostructure shows that they detect light in a broadband range of 600 to 1100 nm with maximum photoresponse of Sb 2 Te 3 , Bi 2 Te 2 Se and Sb 2 Te 3 /Bi 2 Te 2 Se at 1100, 1000, and 1000 nm, respectively. The maximum responsivity values of Sb 2 Te 3 , Bi 2 Te 2 Se, and their heterostructure are 183, 341.8, and 245.9 A W -1 at 1000 nm, respectively. A computational study has also been done using density functional theory (DFT). Using the first-principles methods based on DFT, we have systematically investigated these topological insulators and their heterostructure's electronic and optical properties. The band structures of Sb 2 Te 3 and Bi 2 Te 2 Se thin films (3 QL) and their heterostructure are calculated. The bandgaps of Sb 2 Te 3 and Bi 2 Te 2 Se are 26.4 and 23 meV, respectively, while the Sb 2 Te 3 /Bi 2 Te 2 Se heterostructure shows metallic behaviour. For the optical properties, the dielectric function's real and imaginary parts are calculated using DFT and random phase approximation (RPA). It is observed that these topological materials and their heterostructure are light absorbers in a broadband range, with maximum absorption at 1.90, 2.40, and 3.21 eV.

This communication describes the synthesis, structural investigation and tubulin binding of purine rare imino-tautomer based Ag(i) and Hg(ii)-carbene complexes. These complexes exhibit cytotoxicity through tubulin interaction by binding to a site close to the GTP binding site.

Three copper-N9-modified guanine complexes are reported with structures ranging from a discrete trinuclear motif to a mixed-valence coordination polymer. These complexes were used as precursors for the deposition and growth of copper oxide thin films on Si(100), at two different annealing temperatures, by using a CVD technique. Subsequent resistivity measurements suggest the formation of conductive thin films, raising the possibility of using nucleobase-metal complexes as versatile thin film precursors.

We have synthesized a new photoactive rhenium(i)-complex having a pendant catechol functionality [Re(CO)(3)Cl(L)] (1) (L is 4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) for studying the dynamics of the interfacial electron transfer between nanoparticulate TiO(2) and the photoexcited states of this Re(i)-complex using femtosecond transient absorption spectroscopy. Our steady state absorption studies revealed that complex 1 can bind strongly to TiO(2) surfaces through the catechol functionality with the formation of a charge transfer (CT) complex, which has been confirmed by the appearance of a new red-shifted CT band. The longer wavelength absorption band for 1, bound to TiO(2) through the proposed catecholate functionality, could also be explained based on the DFT calculations. Dynamics of the interfacial electron transfer between 1 and TiO(2) nanoparticles was investigated by studying kinetics at various wavelengths in the visible and near infrared regions. Electron injection into the conduction band of the nanoparticulate TiO(2) was confirmed by detection of the conduction band electron in TiO(2) ([e(-)](TiO(2)(CB))) and the cation radical of the adsorbed dye (1˙(+)) in real time as monitored by transient absorption spectroscopy. A single exponential and pulse-width limited (<100 fs) electron injection was observed. Back electron transfer dynamics was determined by monitoring the decay kinetics of 1˙(+) and .

This communication explores the effect of varying substituent bulk at the N9 position of the adenine moiety and its effect in dictating the structural aspects of silver-adenine frameworks. While adenine alone or 9-benzyl substituted ligand afforded mono and dinuclear dimeric entities, n-propyl substitution at the N9 position results in the formation of a metallaquartet. Longer n-alkyl chains (hexyl and nonyl) resulted in the formation of linear polymeric chains, via N1 and N7 coordination.

This communication reports morphological studies of a novel C(3)-symmetric thiolated, tren-based ditryptophan conjugate. The exposed thiol groups on the soft structures interacted with gold nanoparticles and mediated the release of encapsulated fluorescent dye, when exposed to natural sunlight.

We report the formation of a highly unusual fused, tricyclic purine derivative via N3 alkylation of 9-propargyladenine, upon activation of the acetylenic triple bond by Ag(I) ions. The participation of silver ions in this process might offer newer design paradigms for minor groove N3 DNA alkylation, antibacterial and anticancer agents.

We report the ultrafast charge carrier relaxation dynamics of mercaptopropionic acid capped CdTe quantum dot (QD) using femtosecond transient absorption spectroscopy by exciting the particles with 400 nm laser light and monitoring the transients in the visible to near IR region. Cooling dynamics and population dynamics in different quantized states of the charge carriers were monitored by following the growth kinetics of the bleach at different excitonic positions. The cooling time second and first excitonic states were found to be 150 fs and 500 fs, respectively, which increases non-linearly with its size. Defect states of QD surface play an important role in the cooling dynamics of the charge carriers. Quenching studies have been carried out to find out cooling and trapping dynamics of the individual charge carriers. Electron and hole cooling time were measured to be 700 fs and 150 fs for the first excitonic state using quenchers. Trapping dynamics of electron and hole have been determined by monitoring transient signal at 1000 nm and by using hole and electron quencher, respectively. Electron and hole trapping times have been found to be 700 fs and 1 ps, respectively, in CdTe QD.

We report synthesis and crystallographic studies of a ferrocenyl conjugate of adenine, where the hydrogen bonding interactions promote and stabilize nucleobase homotetrad formation.