Lead halide perovskite materials have attracted significant attention in the context of photovoltaics and other optoelectronic applications, recently, research efforts been directed to nanostructured lead perovskites. Collodial nanocrystals (NCs) cesium halides (CsPbX3, X = Cl, Br, I) exhibit bright photoluminescence, with emission tunable over entire visible spectral region. However, previous studies on CsPbX3 NCs did not address key aspects their chemistry photophysics such as surface...

We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots), by combining Qdot absorbance spectra with detailed elemental analysis suspensions. At high energies, molar extinction coefficient epsilon increases volume d(3) and agrees theoretical calculations using Maxwell-Garnett effective medium theory bulk values for dielectric function. This demonstrates that confinement has no influence on in this spectral range, it provides an...

Inductively coupled plasma mass spectrometry (ICP-MS) was combined with UV–vis−NIR spectrophotometry and transmission electron microscopy to determine the nanocrystal composition molar extinction coefficient ϵ of colloidal PbSe quantum dot (Q-PbSe) suspensions. The ICP-MS results show a nonstoichiometric Pb/Se ratio, systematic excess lead for all samples studied. observed ratio is consistent faceted spherical Q-PbSe model, composed quasi stoichiometric core terminated by Pb surface shell....

PbS Qdots are synthesized using PbCl2 and elemental sulfur as precursors. The available size range is significantly expanded tri-n-octylphosphine (TOP), enabling the synthesis of monodisperse suspensions with a mean varying between 3 10 nm. ligand composition dynamics investigated nuclear magnetic resonance (NMR) spectroscopy. We show that passivated solely by highly dynamic OlAm ligands, even when TOP employed during synthesis. In this respect, compound strongly modifying Qdot synthesis,...

The possibilities offered by 1H solution NMR for the study of colloidal nanocrystal ligands are reviewed. Using CdSe and PbSe nanocrystals with tightly bound oleate as examples, toolbox ligand analysis is introduced, highlighting 1D 1H, diffusion ordered (DOSY) nuclear Overhauser effect (NOESY) spectroscopy techniques that enable to be distinguished from free ligands. For each techniques, it outlined how dynamic stabilization in fast exchange regime affects spectra obtained. Next, shown...

Solution nuclear magnetic resonance spectroscopy (NMR) is used to identify and quantify the organic capping of colloidal PbSe nanocrystals (Q-PbSe). We find that consists primarily tightly bound oleic acid ligands. Only a minor part ligand shell (0-5% with respect number ligands) composed tri- n-octylphosphine. As result, tuning Q-PbSe size during synthesis achieved by varying concentration. By combining NMR results inductively coupled plasma mass spectrometry, complete structural model...

We use solution NMR techniques to analyze the organic/inorganic interface of CdSe quantum dots (Q-CdSe) synthesized using oleic acid as a surfactant. It is shown that resulting Q-CdSe are stabilized by tightly bound species only exchange upon addition free acid. The analysis points toward two-step mechanism where ligands initially physisorbed within ligand shell end up bound, chemisorbed in second step. Importantly, we find every involved this process. By with deuterated carboxyl headgroup,...

We use 1H and 31P solution nuclear magnetic resonance spectroscopy to analyze the binding of phosphonic acid ligands wurtzite CdSe quantum dots (CdSe QDs). QDs synthesized with acids as a surfactant have ligand shell composed anhydride moieties. Titrations as-synthesized excess oleic do not induce desorption species, whereas titration oleic-acid-exchanged shows that latter quantitatively replaces 1:1 stoichiometry. Both stoichiometry acid/phosponic exchange interaction ratio between Cd...

The effect of short-chain alcohols and acetonitrile on the ligand shell composition photoluminescence quantum yield purified PbSe CdSe dots is analyzed by solution NMR spectroscopy. We find that induce release X-type carboxylate ligands with a concurrent reduction yield, while does not. interpret this difference in terms protic or aprotic character both nonsolvents, where only can provide protons needed to desorb ligands. similar differences between when used as nonsolvents during...

Another link in the chain: A thiolactone-based approach for preparation of multifunctionalized sequence-defined oligomeric structures on solid support was established. The iterative aminolysis/chain extension method with a single building block and variety commercial amines allowed protecting group free synthesis various motifs unique backbone preprogrammed organization side chain functionalities. As service to our authors readers, this journal provides supporting information supplied by...

Significance Saponins are plant molecules that produced as a chemical defense against herbivores and eukaryotic pathogens. They constitute structurally diverse, bioactive compounds composed of 30-carbon triterpene backbone adorned with multiple functional groups sugars. Saikosaponins abundant saponins accumulating in the Asian medicinal Bupleurum falcatum , but none enzymes involved their biosynthesis had been characterized. We identified cytochrome P450 oxidation saikosaponins, thereby...

Although solvent–ligand interactions play a major role in nanocrystal synthesis, dispersion formulation, and assembly, there is currently no direct method to study this. Here we examine the broadening of 1H NMR resonances associated with bound ligands turn this poorly understood descriptor into tool assess interactions. We show that line has both homogeneous heterogeneous component. The former nanocrystal-size dependent, latter results from Our model supported by experimental theoretical...

As with every -omics technology, metabolomics requires new methodologies for data processing. Due to the large spectral size, a standard approach in NMR-based implies division of spectra into equally sized bins, thereby simplifying subsequent analysis. Yet, disadvantages are loss information and occurrence artifacts caused by peak shifts. Here, binning algorithm, Adaptive Intelligent Binning (AI-Binning), which largely circumvents these problems, is presented. AI-Binning recursively...

Recently, solution NMR-based approaches have been developed that represent useful new tools for the in situ characterization of capping ligand colloidal nanocrystal dispersions. So far, this development has focused mainly on tightly bound ligands (no exchange) or slow exchange with surface. In such systems, can be identified and its amount interaction quantified via 1D 1H NMR, 1H−13C HSQC, DOSY spectra. Here, we explore case where are fast Using dodecylamine-stabilized CdTe (Q-CdTe|DDA)...

Abstract Triterpenoids are widespread bioactive plant defence compounds with potential use as pharmaceuticals, pesticides and other high-value products. Enzymes belonging to the cytochrome P450 family have an essential role in creating immense structural diversity of triterpenoids across kingdom. However, for many triterpenoid oxidation reactions, corresponding enzyme remains unknown. Here we characterize CYP716 enzymes from different medicinal species by heterologous expression engineered...

While the surface termination of quasi-spherical metal chalcogenide nanocrystals or quantum dots has been widely investigated, it remains unclear whether ensuing chemistry models apply to similar with anisotropic shapes. In this work, we report on surface-chemistry 2D CdSe nanoplatelets, where make use an improved synthesis strategy that yields stable and aggregation free nanoplatelet suspensions a photoluminescence yield as high 55%. We confirm such nanoplatelets are enriched in Cd and, by...

Nanocrystal–ligand interactions and ligand exchange processes are usually described by a uniform distribution of equal binding sites. Here, we analyze this assumption quantitative study the displacement Z-type cadmium oleate ligands from CdSe nanocrystals addition L-type ligands. First, determined stoichiometry reaction analyzing equilibrium upon dilution using solution nuclear magnetic resonance spectroscopy. We found that 1 equiv tetramethylethylene-1,2-diamine (TMEDA) or 2 n-butylamine...

We synthesized HfO2 nanocrystals from HfCl4 using a surfactant-free solvothermal process in benzyl alcohol and found that the resulting could be transferred to nonpolar media mixture of carboxylic acids amines. Using solution (1)H NMR, FTIR, elemental analysis, we studied details transfer reaction surface chemistry sterically stabilized nanocrystals. As-synthesized are charge-stabilized by protons, with chloride acting as counterion. Treatment only does not lead any binding ligands surface....

Abstract In the present work, gelatin type B is modified with highly reactive norbornene functionalities (Gel‐NB) following a one‐pot synthesis approach to enable subsequent thiol–ene photo‐click crosslinking. The modification strategy displays close control over amount of introduced functionalities. Additionally, Gel‐NB exhibits considerably improved processing capabilities in terms two‐photon polymerization when benchmarked earlier‐reported crosslinkable derivatives (e.g.,...

In this manuscript, we compare different analytical methodologies to validate or disprove the binding capabilities of aptamer sequences. This was prompted by lack a universally accepted and robust quality control protocol for characterization performances coupled with observation independent yet inconsistent data sets in literature. As an example, chose three aptamers reported affinity nanomolar range ampicillin, β-lactam antibiotic, used as biorecognition elements several detection...