A new series of all-inorganic lanthanide-containing polyoxometalate (Ln-POM) hybrid clusters, Na5[{Ln6(μ3-OH)3(H2O)9}{SiW9O34}2]·50H2O (1-Ln; Ln3+ = Pr, Nd, Sm, Eu, Gd), featuring a rare 6:2 lanthanide-to-POM motif, has been synthesized. The clusters consist of a hexanuclear {Ln6(μ3-OH)3(H2O)9}15+ unit sandwiched between two achiral trilacunary {A-α-SiW9O34}10- polyanions. Each unit is bridged to three neighboring clusters via Ln-O-W bonds, forming a robust three-dimensional chiral network with srs topology, crystallizing in the cubic I213 space group. Electrospray ionization mass spectrometry studies confirm intact polyanions in variable charge states. The solid-state temperature-dependent photoluminescence studies of 1-Eu reveal the characteristic Eu3+-centered 5D0 → 7FJ (J = 0-4) emissions sensitized via ligand-to-metal charge transfer (LMCT, O→W, 334 nm) transition and direct 4f-4f excitation (5L6 ← 7F0, 396 nm). At 300 K, the LMCT absorption is quenched, and the emission is induced upon direct 4f-4f excitation. The temperature-dependent evolution of the 5D0 → 7F0 transitions underscores the utility of Eu3+ emission as a sensitive probe of site symmetry and dynamic structural modulations. These results highlight the potential of the trilacunary POM {A-α-SiW9O34}10- as an all-inorganic achiral ligand for stabilizing high-nuclearity, light-emissive lanthanide-based sandwich clusters forming a chiral network.

Arrays of amorphous carbon defects were prepared on the basal plane of highly oriented pyrolytic graphite (HOPG) using Ga+ focused ion beam (FIB) writing. These defects were then used as pinning sites for non-IPR C58 fullerene cages (with reactive adjacent pentagon rings) deposited onto the room temperature surface from a low-energy (<6 eV) mass-selected ion beam. Following deposition, a brief annealing step at 550 K increased the occupation of the FIB defects by allowing for pinning of additional C58 cages diffusing from more weakly binding sites elsewhere on the surface. The overall pinning efficiency depends on the lattice constant of the FIB defect array. When the defect spacing approaches the mean gliding length of mobile C58 cages (reflecting surface parallel velocity dissipation following hyperthermal impact on the superlubric HOPG) nearly complete decoration of the FIB defects can be achieved. Upon further heating to 1100 K, a significant fraction of the pinned C58 can be transformed into non-volatile polymers of partially fused cages. Alternatively, heating the C58 island arrays while exposing them to atomic hydrogen can largely remove the FIB-structured deposits by converting them into volatile fullerene hydrides. The results demonstrate a tunable, carbon-on-carbon patterning strategy with potential for nanodevice fabrication.

Adsorption of molecules onto the surface of atomically precise, ligand-protected metal nanoclusters (NCs) is a complex and, unlike ligand exchange, relatively unexplored aspect of NC chemistry. It has significant implications for catalysis as well as for particle nucleation and growth, e.g., in the context of atmospheric chemistry. Here, we investigate the solution-phase adsorption of dithiol molecules, 2,2'-[1,4-Phenylenebis(methylidynenitrilo)]bis[benzenethiol], (abbreviated as R1S2H2) on atomically precise [Ag29(BDT)12]3- NCs (where BDT is 1,3-benzenedithiol). Using electrospray ionization mass spectrometry (ESI MS), high-resolution transmission electron microscopy (HRTEM), and dynamic light scattering (DLS) to probe solution composition after mixing, we resolve rapid adsorption of multiple R1S2H2 secondary ligands onto individual NCs. This is also associated with the formation of NC dimers (detectable by ESI MS) and eventually larger aggregates. Time-dependent measurements at high mass resolution show increasing hydrogen atom loss from the adsorbate modified NCs (and dimers), indicating a transition from a pure physisorptive to a partially chemisorptive state. Molecular docking simulations and density functional theory calculations were used to elucidate the multilayered, soot-particle-like structures of the NC adducts and to establish binding energies for secondary ligand adsorption which govern their assembly and aggregation. These observations provide valuable insights into the complex supramolecular interactions which can occur within the outer shell of NCs exposed to secondary ligands. The observation of the dynamic interplay between physisorptive and chemisorptive phenomena upon aging of the reaction mixture provides important mechanistic insights into the aggregation and growth of nanoscale particles starting from NCs.

Chalcogenido metalate compounds of heavy elements represent an important class of materials, as they offer the opportunity to develop future narrow-band gap semiconductors. Nonclassical syntheses in ionic liquids at moderate temperatures enable access to chalcogenido metalates with unprecedented structural motifs that are not accessible through traditional high-temperature routes. Inspired by the successful ionothermal transformations of Na2[HgTe2] and Na2[Hg3Te4] that recently afforded numerous compounds, we investigated the treatment of K2[Hg2Te3] (A) in various imidazolium-based ionic liquids (ILs) with different cations at room temperature, which yielded a series of compounds. (CmC1Im)6[Hg7Te10] (with m denoting the number of carbon atoms of the alkyl chains attached to the imidazolium ring in 1-position; C1 = Me attached in 3-position; m = 1, 1a; m = 2, 1b), (CmC1Im)4[Hg5Te7] (m = 3, 2a; m = 4, 2b), (C4ImC3ImC4)2[Hg5Te7] (3; C3 = n-Pr attached in 3-position), and (CBnC1Im)2[Hg2Te3] (4; Bn = benzyl) were obtained in (mostly) high crystalline yields and characterized by powder X-ray and single-crystal X-ray diffraction as well as ultraviolet-visible (UV-vis) spectroscopy. In addition, compound 1b, which was formed with the highest selectivity, was subjected to successful upscaling and processing tests, and its thermochromic behavior as well as its thermal properties were investigated by means of temperature-dependent UV-vis spectroscopy and TGA-DSC studies, respectively.

Adsorption of molecules onto the surface of atomically precise, ligand-protected metal nanoclusters (NCs) is a complex and, unlike ligand exchange, relatively unexplored aspect of NC chemistry. It has significant implications for catalysis as well as for particle nucleation and growth, e.g., in the context of atmospheric chemistry. Here, we investigate the solution-phase adsorption of dithiol molecules, 2,2'-[1,4-Phenylenebis(methylidynenitrilo)]bis[benzenethiol], (abbreviated as R1S2H2) on atomically precise [Ag29(BDT)12]3- NCs (where BDT is 1,3-benzenedithiol). Using electrospray ionization mass spectrometry (ESI MS), high-resolution transmission electron microscopy (HRTEM), and dynamic light scattering (DLS) to probe solution composition after mixing, we resolve rapid adsorption of multiple R1S2H2 secondary ligands onto individual NCs. This is also associated with the formation of NC dimers (detectable by ESI MS) and eventually larger aggregates. Time-dependent measurements at high mass resolution show increasing hydrogen atom loss from the adsorbate modified NCs (and dimers), indicating a transition from a pure physisorptive to a partially chemisorptive state. Molecular docking simulations and density functional theory calculations were used to elucidate the multilayered, soot-particle-like structures of the NC adducts and to establish binding energies for secondary ligand adsorption which govern their assembly and aggregation. These observations provide valuable insights into the complex supramolecular interactions which can occur within the outer shell of NCs exposed to secondary ligands. The observation of the dynamic interplay between physisorptive and chemisorptive phenomena upon aging of the reaction mixture provides important mechanistic insights into the aggregation and growth of nanoscale particles starting from NCs.

Elucidating the structural dynamics of ligand-stabilized noble metal nanoclusters (NCs) is critical for understanding their properties and for developing applications. Ligand rearrangement at NC surfaces is an important contributor to structural change. In this study, we investigate the dynamic behavior of ligand-protected [Ag29(L)12]3- NC's (L = 1,3-benzenedithiol) interacting with secondary ligand 2,2'-[1,4-phenylenebis (methylidynenitrilo)] bis[benzenethiol] (referred to as L'). We specifically focus on the structural characteristics of NC-based adducts [Ag29(L)12]L'n3- where n ranges from 1 to 4. This is probed experimentally by using a combination of ultraviolet-visible (UV-vis) spectroscopy, high-resolution electrospray ionization mass spectrometry (ESI MS), and ion mobility mass spectrometry (IM MS) coupled with collision-induced dissociation (MS2 IMS). Density functional theory (DFT) calculations infer comparatively weak noncovalent interactions between the NCs and attached secondary ligands consistent with the fragmentation behavior and experimentally determined collision cross-sections (CCSs), which show a monotonic CCS increase of [Ag29(L)12]L'n3- with an increasing number of L' (n = 1-4). From a detailed analysis of the predicted structures, we infer progressive expansion of the Ag-S staple framework of the precursor NC as secondary ligands are added. Interestingly, detachment of L' from gas-phase [Ag29(L)12]L'n3- by collisional heating yields structures which retain "footprints" of the detached secondary ligands on a millisecond time scale.

Ion mobility spectrometry (IMS) (also including IMS-IMS measurements) as well as DFT calculations have been used to study isomer distributions and isomer interconversion in a range of electrospray-generated lanthanide chloride cluster anions, LnxCl3x+1- (where x = 1-6, and Ln corresponds to the 15 lanthanide elements (except for radioactive Pm)). Where measurement and structural rearrangement timescales allow, we obtain almost quantitative agreement between experiment and theory thus confirming isomer predictions and reproducing isomer intensity ratios. LnxCl3x+1- structures reflect strong ionic bonding with limited directionality. Ring and chain motifs dominate for smaller clusters while for larger clusters more compact three-dimensional structures become favourable. At cluster sizes with two or more closely lying isomers, the lanthanide contraction can lead to systematic variations in structure types across the series.

Non-covalent interactions between polyoxometalates (POMs) and cyclodextrins (CDs) are often utilized to build novel supramolecular architectures for diverse applications. However, structure prediction becomes challenging with the increase in size and complexity of the assemblies. Herein, we investigate the conformer space of isolated non-covalent complexes of a Wells-Dawson type POM [P2W18O62]6- with cyclodextrins (γ-CD) using trapped ion mobility spectrometry (TIMS). We found that the 1 : 1 (POM : CD) complex exhibits one conformer whereas the 1 : 2 and 1 : 3 (POM : CD) complexes exhibit multiple conformers in the gas-phase, despite showing one stable form in their crystalline phase. The observation of distinct conformers in precise supramolecular aggregates of their complexes reflects the possible isomeric pathways in the growth of the assemblies. The structures of the conformers were resolved through a combination of TIMS and theoretical studies (DFT and GFN1-xTB). Moreover, we performed anion photoelectron spectroscopy (PES) studies, which revealed significant electronic stabilization of the POM anions upon complexation in the γ-CD cavity. This was evident from the increase in adiabatic detachment energy (ADE) of the [KPOM(γ-CD)1]5- complex compared to the [KPOM]5- anion by ∼2.4 eV. We also estimated gas-phase binding energies between the POM and γ-CD from the PES studies. Our work provides significant insights into the geometrical and electronic gas-phase structures of POM-CD non-covalent complexes. In the future, this would allow us to precisely design their solid-state assemblies from preformed gas-phase units by mass and isomer-selected ion deposition techniques.

Singlet-triplet gaps in cationic organic dyes are central to many photochemical applications. These typically involve solvated absorbers subjected to poorly characterized environmental perturbations (and spectral shifts). Here we experimentally probe "intrinsic" singlet-triplet gaps in isolation and at T ≈ 5 K. We study two prototypical systems, protonated proflavine and acridine orange, fluorophores with singlet ground states which in solution also have significant triplet quantum yields. Using a two-color, pulsed laser photodissociation (PD) scheme combined with cryogenic ion trapping in the gas phase, we determine vibronically resolved NIR absorptions of metastable triplet state cations tagged with individual helium atoms. Photoluminescence (PL) spectra of the same cationic species deposited into inert neon matrixes allow us to estimate the separation of ground (S0) and lowest-energy triplet (T1) states. Using the same methods, we also measure the corresponding S0-S1 respectively S1-S0 transitions, again resolving vibronic features and locating 0-0 origin bands. TD-DFT calculations using the ωB97X-D functional and cc-pVDZ basis set as well as vertical Hessian modeling as implemented in FCclasses3 satisfactorily describe vibronic features, thus allowing us to assign the experimental spectra as S0-S1/S1-S0, T1-T3, and T1-S0 transitions. At this commonly used level of theory, however, S0-S1 and T1-T3 energy differences are not predicted to be within chemical accuracies. Furthermore, calculated S1-T1 energy gaps are even less reliable.

A new, linear octadentate chelator, "en-pypa," based on 2,2'-bipyridine-6-carboxylic acid, has been developed. This ligand can bind trivalent lanthanoids (e.g., Sm, Eu, Tb, Dy, Tm, Yb, and Lu) very rapidly and yields well-defined complexes that exhibit relatively strong luminescence in aqueous solution. This study reports the synthesis, as well as the structural and photophysical characterization. In addition, nonradiative deactivation of near-infrared luminescence by the ligand N-H oscillators is addressed by comparison of the luminescence from the Yb complexes of en-pypa and its methylated analogue.

Ion mobility spectrometry (IMS) is a powerful technique to determine structures and isomers of gas phase clusters and complex molecules. It is also a valuable tool to investigate ligand-protected atom-precise nanoclusters that cannot be readily crystallized and examined by X-ray diffraction. Here we use IMS to study a diphosphine-protected gold hydride nanocluster, [Au22H3(dppee)7]3+ (dppee = bis(2-diphenylphosphino)ethyl ether), which was synthesized previously and hypothesized to contain two Au11 units with different bridging ligands. Surprisingly, our IMS data revealed the coexistence of two structural isomers in the as-synthesized product with a population of ∼85% for the main isomer and ∼15% for the minor isomer. The two isomers are found to be interconvertible at high activation voltages. Comparison between the IMS data and theoretical calculations confirm that the main and minor isomers consist of one and three bridging ligands, respectively. The isomers and isomerization process uncovered in this work provide opportunities to study the structure-property relationship of atomically precise metal nanoclusters.

Atomically precise clusters such as [Pt17(CO)12(PPh3)8] x+ (x = 1,2) (PPh3 is triphenylphosphine) are known as precursors for making oxidation catalysts. However, the changes occurring to the cluster upon thermal activation during the formation of the active catalyst are poorly understood. We have used a combination of hybrid mass spectrometry and surface science to map the thermal decomposition of [Pt17(CO)12(PPh3)8](NO3)2. High-resolution mass and ion mobility spectrometry together with DFT-based modeling were used to probe the sequence of fragmentation reactions and fragment structures generated upon collisional excitation of [Pt17(CO)12(PPh3)8]2+. This was compared with thermal desorption spectroscopy of [Pt17(CO)12(PPh3)8](NO3)2 dropcast onto an inert graphite surface. In both cases, a characteristic sequence of CO and benzene desorption steps is observed followed at higher excitation energy by H2 loss. This behavior is indicative of Pt-catalyzed C-H activation of phenyl groups during partial stripping of the ligand shell while the Pt17P8 cluster core is retained.

ABSTRACT Carbazolide complexes of lanthanum and terbium with cyclooctatetraenediide (COT) and THF coligands of the type [( dtbp Cbz)LnCOT(thf) n ] (n = 2 for La, 1 for Tb) were synthesized by salt metathesis reactions. The THF molecules were found to be labile, and drying under vacuum led to their partial removal with concomitant formation of the dinuclear complexes [( dtbp Cbz) 2 Ln 2 (COT) 2 (thf)]. The luminescence of both lanthanum and terbium complexes was investigated, and at cryogenic temperatures, strongly temperature‐dependent phosphorescence was observed. The terbium complexes show the expected element‐characteristic emission with narrow lines between 480 and 700 nm upon excitation at 370 nm. Beyond that, broad emission was induced selectively by excitation at lower energy. Related phosphorescence was found for the lanthanum complex, which implies intra‐ or inter‐ligand excitation as source for the latter. This interpretation was corroborated by TD‐DFT computations.

We elucidated how the electronic structure of [Au25(pMBA)18-nH+](n+1)- (pMBA = 4-SC6H4CO2H and n = 0-4), with a superatomic Au13(8e) core, changes with the number of deprotonated pMBA ligands (n) using anion photoelectron spectroscopy (PES) and density functional theory (DFT) calculations. The photoelectron (PE) spectrum of non-deprotonated [Au25(pMBA)18]- exhibited a band with the lowest electron binding energy (EBE) of 4.32 eV. This band was assigned to the electron detachment from 1P orbitals delocalized over the Au13 core. For n = 1, a weak PE band originating from molecular orbitals localized in the CO2- moiety of a pMBA ligand appeared in the EBE region lower than the band originating from the 1P orbital. The EBE of the 1P orbitals of the Au13 core decreased almost linearly with n, from 4.32 eV for n = 0 to -0.84 eV for n = 4. This remarkable reduction in the EBE by more than 5 eV was attributed to electrostatic repulsion from the localized negative charge at the CO2- group(s).

A series of seven-coordinated monoporphyrinate rare-earth(III) complexes featuring a novel tripodal tin-chelated trisphosphineoxide scorpionate ligand with the general formula [(TPP)Ln(PPh2O)3Sn] (Ln = Y, La, Dy, Er, Ho, Yb; TPP = 5,10,15,20-tetraphenylporphyrinate) were synthesized by reactions of the potassium tripodal scorpionate ligand [Sn(PPh2O)3K] with porphyrinate rare-earth metal chlorides [(TPP)LnCl(dme)] (Ln = Y, Dy, Er, Ho, Yb) or porphyrinate lanthanum borohydride [(TPP)LaBH4(thf)2]. The complexes were characterized by single-crystal X-ray diffraction, NMR spectroscopy, and ion mobility mass spectrometry. All complexes emit weak red TPP-based fluorescence, accompanied by near-infrared emission of Er, Ho (rather weak), and Yb (relatively intense with a quantum yield of 1% in dichloromethane solution) of the corresponding complexes. Despite the low intensity, the red fluorescence is characteristic (as referred to the parent free-base TPP) and can be used together with optical absorption for analytical evaluation. Similar photophysical properties can be expected for monoporphyrinate rare-earth metal complexes of other tripodal ligands with a similar binding to the (TPP)Ln moiety.

Collision-induced dissociation and high-resolution cyclic ion mobility mass spectrometry, along with quantum chemical calculations and trajectory simulations, were used to compare the structures of isolated [MAu24(C = CR)(18)](2-), M = Ni, Pd, or Pt, and their associated fragment ions. The three different alkynyl ligand-stabilized (C= CR, R = 3,5-(CF3)2C(6)H(3)), transition metal-doped, gold cluster dianions showed mutually resolvable collision cross sections (CCS), which were ordered consistently with their molecular structures from X-ray crystallography. All three [MAu24(C= CR)(18)](2-) species fragment by sequential diyne loss to form [MAu24(C= CR)(18)-n](2-), with n up to 12. The resultant fragment isomer distributions are significantly n- and M-dependent, and hint at a process involving concerted elimination of adjacent ligands. In particular [NiAu24(C= CR)(18)](2-) also fragments to generate alkyne-oligomers, an inference supported by the parallel observation of precursor dianion isomerization as collision energy is increased.

Ion mobility spectrometry at room temperature was combined with vibrationally resolved electronic spectroscopy of mass-selected ions at 5 K to study the well-known cationic fluorophore acriflavine. One- and two-color photodepletion action spectra recorded in gas-phase (by helium tagging) as well as dispersed fluorescence spectra obtained in neon matrix (after soft-landing deposition) indicate that the primary cation mass electrosprayed from solution comprises two isomers with different optical properties. Theory at the TD-DFT level allowed full spectral assignment. The results have implications for the preparation of novel thin film photonic materials by low-energy ion beam deposition.

Lanthanide metal clusters excel in combining molecular and material chemistry properties. Here, we report an efficient cooperative sensitization UC phenomenon of a Eu3+/Yb3+ nonanuclear lanthanide cluster in CD3OD. The synthesis and characterization of the heteronuclear cluster in the solid state and solution are described together with the UC phenomenon showing Eu3+ luminescence in the visible region upon 980 nm NIR excitation of Yb3+ at concentrations as low as 100 nM. Alongside being the Eu/Yb cluster to display UC (with a quantum yield value of 4.88 × 10-8 upon 1.13 W cm-2 excitation at 980 nm), the cluster exhibits downshifted light emission of Yb3+ in the NIR region upon 578 nm visible excitation of Eu3+, which is ascribed to sensitization pathways for Yb through the 5D0 energy levels of Eu3+. Additionally, a faint emission is also observed at ca. 500 nm upon 980 nm excitation, originating from the cooperative luminescence of Yb3+. The [Eu8Yb(BA)16(OH)10]Cl cluster (BA = benzoylacetonate) is also a field-induced single-molecular magnet (SMM) under 4K with a modest Ueff/kB of 8.48 K, thereby joining the coveted list of Yb-SMMs and emerging as a prototype system for next-generation devices, combining luminescence with single-molecular magnetism in a molecular cluster.