Structural complexity of glyphosate and aminomethylphosphonate metal complexes.

Small differences in the structure and subsequent reactivity of glyphosate complexes can have a highly consequential impact due to the enormous quantities of glyphosate used globally. The gas phase metal speciation of glyphosate and its abundant metabolite, aminomethylphosphonic acid (AMPA), were determined using cross-platform electrospray ionisation ion mobility mass spectrometry. Monomeric [M + L - H] complexes, and both larger, and/or higher order clusters formed with divalent metals (M = Mg, Ca, Sr, Ba, Mn, Co, Cu, and Zn; and L = glyphosate and AMPA).

Tailoring Vacancy Defects in Isolated Atomically Precise Silver Clusters through Mercury-Doped Intermediates.

Vacancy defects are known to have significant effects on the physical and chemical properties of nanomaterials. However, the formation and structural dynamics of vacancy defects in atomically precise coinage metal clusters have hardly been explored due to the challenges associated with isolation of such defected clusters. Herein, we isolate [Ag(BDT)] (BDT is 1,3-benzenedithiol), a cluster with a "missing atom" site compared to [Ag(BDT)], whose precise structure is known from X-ray diffraction.

Elucidating the Structures of Intermediate Fragments during Stepwise Dissociation of Monolayer-Protected Silver Clusters.

Fragmentation dynamics of ligated coinage metal clusters reflects their structural and bonding properties. So far methodological challenges limited probing structures of the fragments. Herein, we resolve the geometric structures of the primary fragments of [Ag L ] , i.

Exploring Isomerism in Isolated Cyclodextrin Oligomers through Trapped Ion Mobility Mass Spectrometry.

Cyclodextrin (CD) macrocycles are used to create a wide range of supramolecular architectures which are also of interest in applications such as selective gas adsorption, drug delivery, and catalysis. However, predicting their assemblies and identifying the possible isomers in CD oligomers have always remained challenging due to their dynamic nature. Herein, we interacted CDs (α, β, and γ) with a divalent metal ion, Cu, to create a series of Cu-linked CD oligomers, from dimers to pentamers.

Carborane-thiol protected copper nanoclusters: stimuli-responsive materials with tunable phosphorescence.

Atomically precise nanomaterials with tunable solid-state luminescence attract global interest. In this work, we present a new class of thermally stable isostructural tetranuclear copper nanoclusters (NCs), shortly Cu@oCBT, Cu@mCBT and Cu@ICBT, protected by nearly isomeric carborane thiols: -carborane-9-thiol, -carborane-9-thiol and -carborane 12-iodo 9-thiol, respectively. They have a square planar Cu core and a butterfly-shaped CuS staple, which is appended with four respective carboranes.

Tunable reactivity of silver nanoclusters: a facile route to synthesize a range of bimetallic nanostructures.

Quantized energy levels and unique optoelectronic properties of atomically precise noble metal nanoclusters (NCs) have made them important in materials science, catalysis, sensors, and biomedicine. Recent studies on the profound chemical interactions of such NCs within themselves and with ultrasmall plasmonic nanoparticles (NPs) indicate that depending on the size, shape, and composition of the second reactant, NCs can either take part in colloidal assembly without any chemical modifications or lead to products with atoms exchanged. Anisotropic NPs are a unique class of plasmonic nanomaterials as their sharp edges and protrusions show higher chemical reactivity compared to flat surfaces, often leading to site-specific growth of foreign metals and metal oxide shells.

Further Dimensions for Sensing in Biofluids: Distinguishing Bioorganic Analytes by the Salt-Induced Adaptation of a Cucurbit[7]uril-Based Chemosensor.

Insufficient binding selectivity of chemosensors often renders biorelevant metabolites indistinguishable by the widely used indicator displacement assay. Array-based chemosensing methods are a common workaround but require additional effort for synthesizing a chemosensor library and setting up a sensing array. Moreover, it can be very challenging to tune the inherent binding preference of macrocyclic systems such as cucurbit[]urils (CB) by synthetic means.

Gas phase ion chemistry of titanium-oxofullerene with ligated solvents.

We investigated the gas phase fragmentation events of highly symmetric fullerene-like (FN-like) titanium oxo-cluster anions, [HTiO(OCH)(HOCH)(HO)] (1) and [HTiO(OCH)(HOCH)(HO)] (2). These oxo-clusters contain a closed cage TiO core, protected by a specific number of methoxy, methanol, and water molecules acting as ligands. These dianionic and monoanionic species were generated in the gas phase by electrospray ionization of the H[Ti(μ-O)(OPr)(OH)] (TOF) cluster in methanol.

NMR Relaxivities of Paramagnetic Lanthanide-Containing Polyoxometalates.

The current trend for ultra-high-field magnetic resonance imaging (MRI) technologies opens up new routes in clinical diagnostic imaging as well as in material imaging applications. MRI selectivity is further improved by using contrast agents (CAs), which enhance the image contrast and improve specificity by the paramagnetic relaxation enhancement (PRE) mechanism. Generally, the efficacy of a CA at a given magnetic field is measured by its longitudinal and transverse relaxivities and , i.

Light-Activated Intercluster Conversion of an Atomically Precise Silver Nanocluster.

Noble metal nanoclusters protected with carboranes, a 12-vertex, nearly icosahedral boron-carbon framework system, have received immense attention due to their different physicochemical properties. We have synthesized -carborane-1,2-dithiol (CBDT) and triphenylphosphine (TPP) coprotected [Ag(CBDT)(TPP)] (shortly Ag) using a ligand-exchange induced structural transformation reaction starting from [AgH(TPP)] (shortly Ag). The formation of Ag was confirmed using UV-vis absorption spectroscopy, mass spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, and multinuclear magnetic resonance spectroscopy.

Kinetics of Intercluster Reactions between Atomically Precise Noble Metal Clusters [Ag(DMBT)] and [Au(PET)] in Room Temperature Solutions.

The kinetics of intercluster metal atom exchange reactions between solvated [Ag(DMBT)] and [Au(PET)] (DMBT and PET are 2,4-dimethylbenzenethiol and 2-phenylethanethiol, respectively, both CHS) were probed by electrospray ionization mass spectrometry and computer-based modeling. Anion mass spectra and collision induced dissociation (CID) measurements show that both cluster monomers and dimers are involved in the reactions. We have modeled the corresponding kinetics assuming a reaction mechanism in which metal atom exchange occurs through transient dimers.

Atom transfer between precision nanoclusters and polydispersed nanoparticles: a facile route for monodisperse alloy nanoparticles and their superstructures.

Reactions between atomically precise noble metal nanoclusters (NCs) have been studied widely in the recent past, but such processes between NCs and plasmonic nanoparticles (NPs) have not been explored earlier. For the first time, we demonstrate spontaneous reactions between an atomically precise NC, Au25(PET)18 (PET = 2-phenylethanethiol), and polydispersed silver NPs with an average diameter of 4 nm and protected with PET, resulting in alloy NPs under ambient conditions. These reactions were specific to the nature of the protecting ligands as no reaction was observed between the Au25(SBB)18 NC (SBB = 4-(tert-butyl)benzyl mercaptan) and the very same silver NPs.

Confining an Ag Core in an Ag Shell: A Four-Electron Superatom with Enhanced Photoluminescence upon Crystallization.

We introduce a cluster coprotected by thiol and diphosphine ligands, [Ag(dppe)(2,5-DMBT)Cl] (dppe = 1,2-bis(diphenylphosphino)ethane; 2,5-DMBT= 2,5-dimethylbenzenethiol), which has an Ag core encapsulated by an Ag(dppe)(2,5-DMBT)Cl shell. The Ag core comprises two Ag distorted trigonal bipyramidal units and is uncommon in Au and Ag nanoclusters. The electrospray ionization mass spectrum reveals that the cluster is divalent and contains four free electrons.

Rapid isotopic exchange in nanoparticles.

Rapid solution-state exchange dynamics in nanoscale pieces of matter is revealed, taking isotopically pure atomically precise clusters as examples. As two isotopically pure silver clusters made of Ag and Ag are mixed, an isotopically mixed cluster of the same entity results, similar to the formation of HDO, from HO and DO. This spontaneous process is driven by the entropy of mixing and involves events at multiple time scales.

Approaching Materials with Atomic Precision Using Supramolecular Cluster Assemblies.

Supramolecular chemistry is a major area of chemistry that utilizes weaker non-covalent interactions between molecules, including hydrogen bonding, van der Waals, electrostatic, π···π, and C-H···π interactions. Such forces have been the basis of several molecular self-assemblies and host-guest complexes in organic, inorganic, and biological systems. Atomically precise nanoclusters (NCs) are materials of growing interest that display interesting structure-property correlations.

A thirty-fold photoluminescence enhancement induced by secondary ligands in monolayer protected silver clusters.

In this paper, we demonstrate that systematic replacement of the secondary ligand PPh3 leads to an enhancement in the near-infrared (NIR) photoluminescence (PL) of [Ag29(BDT)12(PPh3)4]3-. While the replacement of PPh3 with other monophosphines enhances luminescence slightly, the replacement with diphosphines of increasing chain length leads to a drastic PL enhancement, as high as 30 times compared to the parent cluster, [Ag29(BDT)12(PPh3)4]3-. Computational modeling suggests that the emission is a ligand to metal charge transfer (LMCT) which is affected by the nature of the secondary ligand.

Isomerism in Supramolecular Adducts of Atomically Precise Nanoparticles.

We present isomerism in a few supramolecular adducts of atomically precise nanoparticles, [Ag(BDT)∩(CD) ] ( n = 1-6), abbreviated as I where BDT and CD are 1,3-benzenedithiol and cyclodextrins (α, β and γ), respectively; ∩ symbolizes an inclusion complex. The different host-guest complexes of I were characterized in the solution state as well as in the gas phase. The CDs (α, β and γ) encapsulate a pair of BDT ligands protecting the Ag core.

Monolayer-Protected Noble-Metal Clusters as Potential Standards for Negative-Ion Mass Spectrometry.

A detailed mass-spectrometric study of atomically precise monolayer-protected clusters revealed the potential application of such materials as mass-spectrometric standards, mostly in negative-ion mode and in the high-mass range. To date, very few molecules are known that can be efficiently ionized and detected at lower concentrations as negative ions with high signal intensities beyond m/ z 3000. Noble-metal clusters are molecules with definite masses, sizes, and shapes, which makes them excellent candidates to choose as standards over conventional low-molecular-weight polymers or clusters of ionic salts.

Bent Keto Form of Curcumin, Preferential Stabilization of Enol by Piperine, and Isomers of Curcumin∩Cyclodextrin Complexes: Insights from Ion Mobility Mass Spectrometry.

A detailed examination of collision cross sections (CCSs) coupled with computational methods has revealed new insights into some of the key questions centered around curcumin, one of the most intensively studied natural therapeutic agents. In this study, we have distinguished the structures and conformers of the well-known enol and the far more elusive keto form of curcumin by using ion mobility mass spectrometry (IM MS). The values of the theoretically predicted isomers were compared with the experimental CCS values to confirm their structures.

Polymorphism of Ag(BDT)(TPP) cluster: interactions of secondary ligands and their effect on solid state luminescence.

We present the first example of polymorphism (cubic & trigonal) in single crystals of an atomically precise monolayer protected cluster, Ag29(BDT)12(TPP)43-. We demonstrate that C-Hπ interactions of the secondary ligands (TPP) are dominant in a cubic lattice compared to a trigonal lattice, resulting in a greater rigidity of the structure, which in turn, results in a higher luminescence efficiency in it.

Understanding proton capture and cation-induced dimerization of [Ag(BDT)] clusters by ion mobility mass spectrometry.

Proton transfer reactions have been a topic of fundamental interest in several areas of chemistry and biology. However, such reactivity has not been explored in detail for nanoscale materials. In this article, we present a unique reaction of an atomically precise monolayer-protected silver nanocluster, [Ag(BDT)], with a proton (H).

Fullerene-Functionalized Monolayer-Protected Silver Clusters: [Ag(BDT)(C) ] ( n = 1-9).

We report the formation of supramolecular adducts between monolayer-protected noble metal nanoclusters and fullerenes, specifically focusing on a well-known silver cluster, [Ag(BDT)], where BDT is 1,3-benzenedithiol. We demonstrate that C molecules link with the cluster at specific locations and protect the fragile cluster core, enhancing the stability of the cluster. A combination of studies including UV-vis, high-resolution electrospray ionization mass spectrometry, collision-induced dissociation, and nuclear magnetic resonance spectroscopy revealed structural details of the fullerene-functionalized clusters, [Ag(BDT)(C) ] ( n = 1-9).