Iodide Clusters Research Articles

Ligand-Induced Formation of Copper(I) Iodide Clusters: Exocyclic Coordination Polymers with Bis-dithiamacrocycle Isomers.

A comparative study on the formation of guest clusters induced by different shapes (or sizes) of exocyclic binding sites embedded in the bis-macrocyclic host isomers is reported. CuI reacts with two regioisomers of a bis-dithiamacrocycle, o-bis-L (W-shaped binding site) and m-bis-L (U-shaped binding site), to yield one-dimensional coordination polymers {[(μ4-Cu4I4)(o-bis-L)]·2CH3CN}n (1a) and [(μ4-Cu2I2)(m-bis-L)]n (2). In 1a, the o-bis-L ligand isomer is linked by a spacious cubane [Cu4I4] cluster, while the m-bis-L ligand in 2 is linked by a smaller rhomboid [Cu2I2] cluster because of the different exocyclic binding sites. The results observed illustrate the possibility for the metal clusters including [CunIn] (n = 2 or 4) to adopt a controlled formation through the binding site alternation or design. Because of the adaptive cluster formations, the products show different photophysical properties. Additionally, sliding of the one-dimensional chains in 1a was observed upon loss of the lattice solvent molecules in ambient condition.

Two-semiconductive-component hybrid coordination polymers with controllable photo-induced electron-transfer properties.

Two semiconductive inorganic-organic hybrid coordination polymers constructed from metal iodide clusters and naphthalene diimide semiconductive components, [Cu2I2(DPNDI)]n () and [PbI2(DPNDI)]n () (DPNDI = N,N'-di-(4-pyridyl)-1,4,5,8-naphthalene diimide), have been synthesized and characterized. Although possessing similar 2D heterostructures, hybrids exhibited different photo-induced electron-transfer properties. Due to the higher HOMO energy level of the [Cu2I2]n chain than that of the [PbI2]n cluster, only hybrid can easily undergo intramolecular electron transfer to form a long-lived charge separated state, which may be applied in artificial photosynthesis.

A photobleaching resistant polymer supported hexanuclear molybdenum iodide cluster for photocatalytic oxygenations and photodynamic inactivation of Staphylococcus aureus.

The ability of a hexanuclear molybdenum cluster, [Mo6I8(CH3COO)6]2-, to carry out, upon irradiation, singlet oxygen mediated photocatalytic oxygenation reactions has been tested. This complex has been also supported on a solid polymeric matrix, yielding an immobilized photosensitizer with remarkable photostability and recyclability. Preliminary studies of antibacterial photoinactivation of Staphylococcus aureus have been conducted, with positive results.

Ellipticity-dependent of multiple ionisation methyl iodide cluster using 532 nm nanosecond laser

ABSTRACTThe dependence of multiply charged ions on laser ellipticity in methyl iodide clusters with 532 nm nanosecond laser was measured using a time-of-flight mass spectrometer. The intensities of multiply charged ions Iq+(q = 2–4) with circularly polarised laser pulse were clearly higher than those with linearly polarised laser pulse but the intensity of single charged ions I+ was inverse. And the dependences of ions on the optical polarisation state were investigated and a flower petal and square distribution for single charged ions (I+, C+) and multiply charged ions (I2+, I3+, I4+, C2+) were observed, respectively. A theoretical calculation was also proposed to simulate the distributions of ions and theoretical results fitted well with the experimental ones. It indicated that the high multiphoton ionisation probability in the initial stage would result in the disintegration of big clusters into small ones and suppress the production of multiply charged ions.

Synthesis, crystal structure, and luminescence properties of complexes (4-ViBnNMe3)2[{M6(µ3-I)8}I6] (M = Mo, W; (4-ViBnNMe3)+ is trimethyl(4-vinylbenzyl)ammonium)

Two new compounds based on octahedral molybdenum and tungsten iodide cluster complexes of the composition (4-ViBnNMe3)2[{M6(µ3-I)8}I6] (M = Mo, W; (4-ViBnNMe3)+ is trimethyl(4-vinylbenzyl)ammonium) were synthesized and structurally characterized. The luminescence properties of powder samples of the synthesized compounds and of the salts (Bu4N)2[{M6(µ3-I)8}I6] described earlier were investigated. Due to the presence of the vinylcontaining cation, these compounds can be involved in radical copolymerization in order to produce polymeric luminescent materials.

Pressure Control of Cuprophilic Interactions in a Luminescent Mechanochromic Copper Cluster.

For the development of applications based on mechanochromic luminescent materials, a comprehensive study of the mechanism responsible for the emission changes is required. We report the study of a mechanochromic copper iodide cluster under hydrostatic pressure, which allows control of crystal packing via modification of the intermolecular interactions. In situ single-crystal powder X-ray diffraction analysis and emission measurements under pressure permit one to establish a direct correlation between the molecular structure and luminescence properties and, in particular, to demonstrate that cuprophilic interactions are responsible for the stimuli-responsive luminescence properties of such multinuclear coordination compounds.

Analysis of heterogeneous water vapor uptake by metal iodide cluster ions via differential mobility analysis-mass spectrometry.

The sorption of vapor molecules onto pre-existing nanometer sized clusters is of importance in understanding particle formation and growth in gas phase environments and devising gas phase separation schemes. Here, we apply a differential mobility analyzer-mass spectrometer based approach to observe directly the sorption of vapor molecules onto iodide cluster ions of the form (MI)xM(+) (x = 1-13, M = Na, K, Rb, or Cs) in air at 300 K and with water saturation ratios in the 0.01-0.64 range. The extent of vapor sorption is quantified in measurements by the shift in collision cross section (CCS) for each ion. We find that CCS measurements are sensitive enough to detect the transient binding of several vapor molecules to clusters, which shift CCSs by only several percent. At the same time, for the highest saturation ratios examined, we observed CCS shifts of up to 45%. For x < 4, cesium, rubidium, and potassium iodide cluster ions are found to uptake water to a similar extent, while sodium iodide clusters uptake less water. For x ≥ 4, sodium iodide cluster ions uptake proportionally more water vapor than rubidium and potassium iodide cluster ions, while cesium iodide ions exhibit less uptake. Measured CCS shifts are compared to predictions based upon a Kelvin-Thomson-Raoult (KTR) model as well as a Langmuir adsorption model. We find that the Langmuir adsorption model can be fit well to measurements. Meanwhile, KTR predictions deviate from measurements, which suggests that the earliest stages of vapor uptake by nanometer scale species are not well described by the KTR model.

Subtle Modulation of Cu4X4L2 Phosphine Cluster Cores Leads to Changes in Luminescence.

A series of Cu4X4(PPh2py)2 compounds (X = Cl (1), Br (2), I (3), PPh2py = 2-(diphenylphosphino)pyridine) were prepared and characterized using X-ray crystallography, NMR, UV-vis, and luminescence spectroscopy. The copper chloride and bromide clusters have Cu4X4 octahedral cores while the copper iodide clusters contain an unprecedented butterfly shaped core. Crystallization of the copper bromide and iodide clusters from the appropriate solvent produced the solvates 2·2CH2Cl2, 2·2CHCl3, and 3·0.5CH2Cl2 where the presence of the lattice solvate influences the overall structural properties. Using TD-DFT calculations, the emission was assigned to a mixed metal- and halide-to-ligand charge transfer, (M + X)LCT. Subtle differences in the copper core geometry and μ-halide bonding perturb the emissions of these copper(I) halide clusters.

Geometry flexibility of copper iodide clusters: variability in luminescence thermochromism.

An original copper(I) iodide cluster of novel geometry obtained by using a diphosphine ligand is reported and is formulated [Cu6I6(PPh2(CH2)3PPh2)3] (1). Interestingly, this sort of "eared cubane" cluster based on the [Cu6I6] inorganic core can be viewed as a combination of the two known [Cu4I4] units, namely, the cubane and the open-chair isomeric geometries. The synthesis, structural and photophysical characterisations, as well as theoretical study of this copper iodide along with the derived cubane (3) and open-chair (2) [Cu4I4(PPh3)4] forms, were investigated. A new polymorph of the cubane [Cu4I4(PPh3)4] cluster is indeed presented (3). The structural differences of the clusters were analyzed by solid-state nuclear magnetic resonance spectroscopy. Luminescence properties of the three clusters were studied in detail as a function of the temperature showing reversible luminescence thermochromism for 1 with an intense orange emission at room temperature. This behavior presents different feature compared to the cubane cluster and completely contrasts with the open isomer, which is almost nonemissive at room temperature. Indeed, the thermochromism of 1 differs by a concomitant increase of the two emission bands by lowering the temperature, in contrast to an equilibrium phenomenon for 3. The luminescence properties of 2 are very different by exhibiting only one single band when cooled. To rationalize the different optical properties observed, density functional theory calculations were performed for the three clusters giving straightforward explanation for the different luminescence thermochromism observed, which is attributed to different contributions of the ligands to the molecular orbitals. Comparison of 3 with its [Cu4I4(PPh3)4] cubane polymorphs highlights the sensibility of the emission properties to the cuprophilic interactions.

Mechanochromic luminescence of copper iodide clusters.

Luminescent mechanochromic materials are particularly appealing for the development of stimuli-responsive materials. Establishing the mechanism responsible for the mechanochromism is always an issue owing to the difficulty in characterizing the ground phase. Herein, the study of real crystalline polymorphs of a mechanochromic and thermochromic luminescent copper iodide cluster permits us to clearly establish the mechanism involved. The local disruption of the crystal packing induces changes in the cluster geometry and in particular the modification of the cuprophilic interactions, which consequently modify the emissive states. This study constitutes a step further toward the understanding of the mechanism involved in the mechanochromic luminescent properties of multimetallic coordination complexes.

Assembly of photoluminescent [CunIn] (n = 4, 6 and 8) clusters by clickable hybrid [N,S] ligands

The controlled growth of luminescent copper(i)-iodide clusters has been achieved by tuning the structure of hybrid NS ligands using click chemistry.

Ionisation of methyl iodide clusters using nanosecond laser pulses: detection of multiply charged positive ions, negative ions and energetic electrons

Methyl iodide clusters have been ionised using laser pulses of intensity ∼109 W cm−2 at 266, 355, 532 and 1064 nm and the ions produced in the laser–cluster interaction were analysed with a time-of-flight mass spectrometer.

A frequency and amplitude scanned quadrupole mass filter for the analysis of high m/z ions.

Quadrupole mass filters (QMFs) are usually not used to analyze high m/z ions, due to the low frequency resonant circuit that is required to drive them. Here we describe a new approach to generating waveforms for QMFs. Instead of scanning the amplitude of a sine wave to measure the m/z spectrum, the frequency of a trapezoidal wave is digitally scanned. A synchronous, narrow-range (<0.2%) amplitude scan overlays the frequency scan to improve the sampling resolution. Because the frequency is the primary quantity that is scanned, there is, in principle, no upper m/z limit. The frequency signal is constructed from a stabilized base clock using a field programmable gate array. This signal drives integrating amplifiers which generate the trapezoidal waves. For a trapezoidal wave the harmonics can be minimized by selecting the appropriate rise and fall times. To achieve a high resolving power, the digital signal has low jitter, and the trapezoidal waveform is generated with high fidelity. The QMF was characterized with cesium iodide clusters. Singly and multiply charged clusters with z up to +5 were observed. A resolving power of ∼1200 (FWHM) was demonstrated over a broad m/z range. Resolution was lost above 20,000 Th, partly because of congestion due to overlapping multiply charged clusters. Ions were observed for m/z values well in excess of 150,000 Th.

Hydrothermal synthesis and solid-state structures of polynuclear technetium iodide compounds

Two new technetium iodide compounds, Tc2(O2CCH3)4I and K[Tc8(μ-I)8I4]I, were synthesized in an autoclave from the reaction of KTcO4 in glacial acetic acid with hydroiodic acid and/or alkali metal iodide salts at 210°C under 60–70atm hydrogen pressure. The structures of Tc2(O2CCH3)4I and K[Tc8(μ-I)8I4]I were solved by single-crystal X-ray diffraction. The compound Tc2(O2CCH3)4I crystallizes in the monoclinic space group C2/m with a=7.1194(6)Å, b=14.5851(13)Å, c=7.1586(6)Å, and β=110.9540(10)°. The structure of Tc2(O2CCH3)4I consists of infinite chains of Tc2(O2CCH3)4+ units linked by bridging iodides, an arrangement similar to the one found in Tc2(O2CCH3)4X (X=Cl, Br). The TcTc separation in Tc2(O2CCH3)4I (i.e., 2.1146(4)Å) is consistent with the presence of a TcTc bond of order 3.5. Magnetic susceptibility measurements reveal Tc2(O2CCH3)4I to be paramagnetic (μeff=1.84B.M.) and support the electronic configuration σ2π2δ2δ∗1 for the Tc25+ unit in the compound. The compound K[Tc8(μ-I)8I4]I crystallizes in the monoclinic space group P21/n with a=8.0018(5)Å, b=14.5125(10)Å, c=13.1948(9)Å, and β=102.3090(10)°, and is the first octanuclear technetium iodide cluster to be reported. The TcTc separations in the [Tc8(μ-I)8I4] cluster (i.e., 2.164(3)Å, 2.5308(8)Å and 2.72(3)Å) suggest the presence of TcTc triple bonds, TcTc double bonds and TcTc single bonds.

Polymorphic copper iodide clusters: insights into the mechanochromic luminescence properties.

An in-depth study of mechanochromic and thermochromic luminescent copper iodide clusters exhibiting structural polymorphism is reported and gives new insights into the origin of the mechanochromic luminescence properties. The two different crystalline polymorphs exhibit distinct luminescence properties with one being green emissive and the other one being yellow emissive. Upon mechanical grinding, only one of the polymorphs exhibits great modification of its emission from green to yellow. Interestingly, the photophysical properties of the resulting partially amorphous crushed compound are closed to those of the other yellow polymorph. Comparative structural and optical analyses of the different phases including a solution of clusters permit us to establish a correlation between the Cu-Cu bond distances and the luminescence properties. In addition, the local structure of the [Cu4I4P4] cluster cores has been probed by (31)P and (65)Cu solid-state NMR analysis, which readily indicates that the grinding process modifies the phosphorus and copper atoms environments. The mechanochromic phenomenon is thus explained by the disruption of the crystal packing within intermolecular interactions inducing shortening of the Cu-Cu bond distances in the [Cu4I4] cluster core and eventually modification of the emissive state. These results definitely establish the role of cuprophilic interactions in the mechanochromism of copper iodide clusters. More generally, this study constitutes a step further into the understanding of the mechanism involved in the mechanochromic luminescent properties of metal-based compounds.

Synthesis, spectroscopic characterization, and crystal structures of copper(I) iodide clusters of N-methylthiourea and 1,3-diazinane-2-thione

Two copper(I) iodide complexes, [Cu4(Metu)6I4] (I) and [Cu8(Diaz)12I8] (II) (Metu = N-methylthiourea; Diaz = 1,3-diazinane-2-thione), have been prepared and their structures been determined by X-ray crystallography. The crystal structures show that complex I is a tetranuclear, while II is an octanuclear cluster, both having a Cu : S ratio of 2 : 3, characteristic of metallothioneins. In I, each of the four copper atoms is coordinated to three thiourea ligands and one iodide ion in a distorted tetrahedral mode adopting admantane-like structure. In II, four types of core arrangements are observed around copper(I), which include, Cu(μ-S2)I2, Cu(μ-S2)(μ-I)I, Cu(μ-S3)I, and Cu(μ-S3)S each having copper(I) tetrahedrally coordinated. The complexes were also characterized by IR and 1H and 13C NMR spectroscopy.

Mechanochemical preparation of copper iodide clusters of interest for luminescent devices.

The copper iodide complexes are known for their large variety of coordination geometries. Such diversity, while making it difficult to predict the final structure, permits the preparation of a great number of copper iodide complexes based on the same ligand. The target of the research was that of thoroughly exploring the chemistry of CuI and the ligand diphenyl-2-pyridyl phosphine (PN) by varying the stoichiometric ratio and/or the aggregation state. Six different compounds have been identified: [Cu4I4(PN)2], [Cu4I4(PN)2·(CH2Cl2)0.5], [CuI(PN)0.5]∞, [CuI(PN)3] whose structures have been determined during this study, CuI(PN)2 which was characterized by powder diffraction and [Cu2I2(PN)3] which has been already reported. The preparation routes are also different: synthesis in solution yielded [Cu4I4(PN)2·(CH2Cl2)0.5] and [CuI(PN)3] while [CuI(PN)0.5]∞ and CuI(PN)2 were obtained only via solid state reactions. These two latter examples confirmed that mechanochemistry is a valid route to explore the landscape of the possible structures of CuI derivatives. Crystallization by traditional solution procedures failed to give the desired crystal, so structure determination of the new compounds was tackled in two ways: by attempting crystal growth via solvothermal synthesis and by resolving the structure from X-ray powder diffraction data with "direct space" methods. What is more the photophysical properties of the complexes that could be obtained as sufficiently pure powders have also been investigated and are reported herein.

A cationic copper(I) iodide cluster MOF exhibiting unusual ligand assisted thermochromism.

By employing a tridentate thiophosphoramide ligand, [(NHAQ)3P[double bond, length as m-dash]S] (AQ = 3-quinolinyl), a cationic MOF, {[Cu6I5(L(1))2](OH)·3DMF·2.5MeOH}n, was synthesized. Photo-physical studies on the 2D-MOF showed an unusual thermochromic behaviour emitting a blue fluorescence at 298 K due to the AQ chromophore and an orange-yellow phosphorescence at 77 K due to the [Cu6I5](+) unit.

Synthesis, Spectroscopic Characterization, and Crystal Structures of Copper(I) Iodide Clusters of N-Methylthiourea and 1,3-Diazinane-2-Thione

Synthesis, Spectroscopic Characterization, and Crystal Structures of Copper(I) Iodide Clusters of N-Methylthiourea and 1,3-Diazinane-2-Thione

Anion Distribution in Superionic Ag3PO4–AgI Glasses Revealed by Dipolar Solid-State NMR

The structure of roller-quenched fast ion conductive glasses (FICs) (Ag3PO4)x(AgI)1–x (0.15 ≤ x ≤ 0.50) is investigated by 109Ag and 31P solid-state NMR spectroscopies. Monotonic linear dependences of 109Ag and 31P chemical shifts on x are consistent with a statistical distribution of the phosphate and iodide anions. This conclusion is quantitatively confirmed by a new 31P homonuclear magnetic dipolar recoupling method, termed double-quantum-based dipolar recoupling effects nuclear alignment reduction (DQ-DRENAR), which numerically proves a random spatial distribution of the phosphate anions. Altogether these results give the final answer to a long-standing debate on the structure of silver in AgI-based (FIC) glasses, proving the absence of previously postulated silver iodide cluster domains.