Patent Application
20240262853
The disclosed technology is generally directed to extraction of metals, such as platinum. More particularly the technology is directed to hexachloroplatinate(IV) dianions with a cucurbituril.
Anion recognition has become one of the most active areas for research in supramolecular chemistry, since anions play crucial roles in biological, environmental and materials sciences. Following its vigorous growth during the past several decades, anion recognition has spawned a number of applications, including anion extraction and separation, anion sensing, transmembrane transport, and organocatalysis. In this context, many well-crafted artificial macrocyclic anion-receptors, e.g., crown ethers, calixarenes, calix[4]pyrroles, cyanostars, bambus[6]urils, biotin[6]uril esters, cyclopeptides, and others have been synthesized, which exhibit highly specific recognition for particular anions. The [PtCl6]2− dianion, a stable platinum metalate, is a key intermediate in the platinum-mining process and an indispensable upstream product in the platinum-chemical industry. In recent years, the demand for platinum has been increasing steadily.
It has found a wide range of applications in chemical synthesis, jewelry manufacture, electronic fabrication, automotive exhaust gas treatment, and anticancer drug production. It follows that the development of molecular receptors, which are capable of recognizing and separating [PtCl6]2− dianions selectively, is significant to the recovery of platinum metal. There are only a handful of reports, however, on receptors for [PtCl6]2− dianions, including hydrazine-functionalized zeolites, p-diethylaminomethylthia-calix[4]arene, and tripodal ionophores, which either adsorb [PtCl6]2− dianions in their porous channels or bind them in their cavities. It is clear that there is a need to development of more efficient ways to probe the selective recognition and separation of [PtCl6]2− dianions and the like.
Disclosed herein are compounds, compositions, and methods for separating dianions, such as [PtCl6]2−, with a cubcurbituril, such as cucurbit[6]uril, is disclosed herein. The presently disclosed technology may be used for extraction of metals, such as platinum. The use of the present technology allows for platinum extraction from spent vehicular three-way catalytic converters and other platinum-bearing metal waste. The present technology allows for selective recognition of [PtCl6]2− dianion dianions through noncovalent bonding interactions on the outer surface of CB[6], selective co-crystallization with [PtCl6]2− dianion with CB[6] even in the presence of [PdCl4]2− and [RhCl6]3− anions; co-precipitation within seconds at ambient conditions; and recovery of platinum from its mixtures in an environmentally friendly manner.
Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention.
Disclosed herein are high-efficiency platinum recovery methods utilizing cucurbiturial. The composition and methods described herein provide an environmentally benign, highly efficient, and thoroughly selective processes for platinum recovery. As further described herein, contacting a macrocycle with platinum halide anions creates adducts where the platinum halide anions are reversibly bound to the outer surface of the macrocycle by non-covalent interactions, allowing of the efficient production of precipitates that may be separated from their platinum bearing source material.
The Exampled demonstrate instantaneous co-crystallization and concomitant co-precipitation of dianions through noncovalent bonding interactions on the outer surface of a cucurbitil, such as [PtCl6]2− dianions and cucurbit[6]uril, a phenomenon which relies on the selective recognition of these dianions through noncovalent bonding interactions on the outer surface of cucurbit[6]uril. The selective [PtCl6]2− dianion recognition is driven by the weak [Pt—Cl . . . H—C] hydrogen bonding and [Pt—Cl . . . C═O] ion-dipole interactions. The synthetic protocol is highly selective. It is not observed in combinations between cucurbit[6]uril and other Pt- and Pd- or Rh-based chloride anions. We have also demonstrated that cucurbit[6]uril is able to separate selectively [PtCl6]2− dianions from a mixture of [PtCl6]2−, [PdCl4]2− and [RhCl6]3− anions. This highly selective and fast co-crystallization protocol allows for recovery of platinum from spent vehicular three-way catalytic converters and other platinum-bearing metal waste.
An “adduct” is a new chemical species AB, each molecular entity of which is formed by direct combination of two separate molecular entities A and B in such a way that there is change in connectivity, but no loss, of atoms within the moieties A and B. Stoichiometries other than 1:1 are also possible, such as 2:1, 3:1, 4:1 and so forth.
The adduct is formed from a metal halide anion non-covalently bound to the outer surface of a macrocycle. Macrocycles are a cyclic macromolecular or a macromolecular cyclic portion of a macromolecule. A molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass.
Suitably the macrocycle is a cucurbituril. A “cucurbituril” is macrocyclic molecule made of glycoluril (═C4H2N4O2═) monomers linked by methylene bridges (—CH2—). Cucurbituril may generically be referred to as cucurbit[n]uril or CB[n] wherein n is the number of glycoluril units. An exemplary method of preparing CB[n] is shown in Scheme 1.
Cucurbiturils are amidals and synthesized from urea 1 and a dialdehyde (e.g., glyoxal 2) via a nucleophilic addition to give the intermediate glycoluril 3. This intermediate is condensed with formaldehyde to give hexamer cucurbit[6]uril above 110° C. Ordinarily, multifunctional monomers such as 3 would undergo a step-growth polymerization that would give a distribution of products, but due to favorable strain and an abundance of hydrogen bonding, the hexamer 5 is the only reaction product isolated after precipitation.
Other cucurbiturils may also be prepared with differing numbers of glycoluril units. Decreasing the temperature of the reaction to allows access to other sizes of cucurbiturils, including CB[5], CB[7], CB[8], and CB[10]. CB[6] may still be the major product with the other ring sizes formed in smaller yields. The isolation of sizes other than CB[6] requires fractional crystallization and dissolution.
Cucurbit[6]uril (CB[6]) possesses (
The metal halide anion comprises a noble metal. In some embodiments, the metal halide anion is a octahedral anion such as [MX6]2− where M is a noble metal, such as Pt, and X is a halide. Each halide may be the same, such as for [PtCl6]2− or [PtBr6]2−. In other embodiments, the metal halide anion may comprise two or more different halides. In some embodiments, the metal halide anion is provided with a counter anion such as H+ or metal cation, such as an alkali cation.
Superstructures and crystalline compositions may be formed from adducts described herein. A “crystalline composition” is a material whose constituents are arranged in a highly ordered microscopic structure, forming a crystal lattice. A “superstructure” is a material having additional structure superimposed upon a given crystalline material, supramolecular assembly, or other well-defined substructure.
A “supramolecular assembly” is a well-defined complex of molecules held together by noncovalent bonds. Suitably, supramolecular assemblies may have well defined order in one, two, or three dimensions. The supramolecular assemblies described herein between the platinum halide anion and the outer surface of the macrocycle may include hydrogen bonds and/or ion-dipole interactions, such as [Pt—X . . . H—C] and [Pt—X . . . C═O], respectively.
The compositions described herein may be used for the isolation and recovery of Pt from platinum-bearing materials. A “platinum-bearing material” is material comprised of platinum atoms, regardless of oxidation state. Exemplary platinum-bearing materials include, without limitation, ores, metal mixtures, or post-consumer products.
The term “metal mixture” refers to two or more elements from Groups IA, IIA, IB to VIIIB, the lanthanide series and actinide series of the periodic table. An example of a metal mixture is Au and Pt.
The term “post-consumer product” refers to any man-made product for consumption, bartering, exchange or trade. Examples of “post-consumer product” include a catalytic material, jewelry item, an electronics item, precious metal products, and coins, among others.
The term “catalytic material” includes any substance that increases the rate of a chemical reaction without modifying the overall standard Gibbs energy change in the reaction. Catalytic materials may be homogeneous or heterogeneous. Exemplary catalytic materials include, without limitation, those found in a catalytic converter.
The term “jewelry item” includes any aesthetic item that includes as one component a precious metal. Examples of a jewelry item include a ring, a bracelet and a necklace, among others.
The term “electronics item” refers to a product that includes at least one circuit for conducting electron flow. Examples of an electronics item include a computer, a monitor, a power supply, an amplifier, and a preamplifier, a digital to analog converter, an analog to digital converter, and a phone, among others.
The term “precious metal product” includes a partially purified form or a purified form of a noble metal, such as gold, platinum, palladium and silver. Examples of a precious metal include a powder, ingot, or bar of gold, silver, platinum, among others. As used herein, “partially-purified form” refers to a form having from about 10% to about 75% of the pure form of a noble metal. As used herein, “purified form” refers to a form having greater than about 75% of the pure form of a noble metal.
The term “coin” refers to any pressed object composed of a pure metal, mixed metal or metal alloy that can be used as a currency, a collectable, among other uses. As used herein, “pure metal” refers to a single metal of at least 95% or greater purity. As used herein “mixed metal” refers to two or more metals. As used herein “metal alloy” refers to a mixture or solid solution of a metal with at least one other element.
A method for isolating and recovering platinum from platinum-bearing materials was developed based upon the selective co-precipitation of metal halide anions non-covalently bound to the outer surface of macrocycles. Referring to
The macrocycle may be added to the platinum halide solution to form a precipitate 104. Suitably the macrocycle is a cucurbituril, such as CB[6]. The precipitate may comprise any of the adducts, superstructure, or crystalline materials described herein. In some embodiments, the precipitate [PtX6]2− is bound to the outer surface of CB[6].
The precipitate is isolated from the metal halide salutation 106. Any means of isolation can be used to obtain precipitate, include filtration, centrifugation, and other separation methods known in the art.
In some embodiments, not all of platinum-bearing material can be dissolved in platinum halide solution. As a result, some solid remnants of platinum-bearing material (whether or not including platinum) can persist. In such aspects, it may be desirable to include a filtration step to remove the solid remnants prior to subsequent processing. The resultant filtrate may be processed as described above to obtain the isolated platinum.
The precipitate can be treated with a reducing agent to produce elemental platinum (Pt(0)) 108. Examples of reducing agents include, but are not limited to, N2H4, NaBH4, Na2S2O5, and H2C2O4, among others. The elemental platinum can be readily isolated as a precipitate and the macrocycle can be harvested in the liquid phase and recycled for reuse to precipitate additional platinum 110.
An exemplary aspect of the process outlined generally in
The method for isolating and recovering platinum from platinum-bearing materials has several applications. In one aspect, the method can be applied to isolating platinum from platinum-bearing material, wherein the platinum-bearing material is selected from an ore, a metal mixture, or a post-consumer product. The foregoing examples of isolating platinum from platinum-bearing materials are not limited to the foregoing materials. The specific etching and leaching process for dissolving platinum from platinum-bearing materials results in formation of a specific platinum-halide compound that can be recovered in the form of a complex with the macrocycle, thereby rendering the method suitable for recovering platinum from each of these particular applications as well as other platinum-bearing materials.
The Examples demonstrate highly specific formation of a supramolecular crystalline material, facilitated by the selective recognition of [PtCl6]2− dianions on account of the outer surface interactions with CB[6]. The formation of the supramolecular cocrystals have been confirmed by Raman, X-ray photoelectron, SEM-equipped energy-dispersive X-ray spectroscopies, and their solid-state superstructures have been characterized by single-crystal and powder X-ray diffraction analyses. The rapid co-crystallization and spontaneous co-precipitation between CB[6] and [PtCl6]2−, which is highly specific, do not manifest themselves in the case of six other Pt-, Pd-, and Rh-based chlorides. In proof-of-principle investigations, we have demonstrated the CB[6] can serve as an extractant to separate the [PtCl6]2− dianions in the presence of [PdCl4]2− and [RhCl6]3− anions. This highly selective and fast co-crystallization process may be used for platinum-recovery from spent three-way catalytic converters of vehicles.
Upon addition of a 4 M HCl solution of CB[6] (1.0 mL, 10.0 mM) to aqueous solutions of H2PtCl6, (NH4)2PtCl4, cisplatin and transplatin (1.0 mL, 10.0 mM) at room temperature, a yellow suspension formed exclusively between H2PtCl6 and CB[6]. See
Scanning electron microscopy (SEM) was employed to investigate the topological morphology and elemental distribution in these microcrystals formed between CB[6] and H2PtCl6. In the SEM images (
In order to gain insight into the noncovalent bonding forces behind the instantaneous co-crystallization between CB[6] and H2PtCl6, a single-crystal X-ray diffraction analysis was carried out. High quality yellow crystals of CB[6]·H2PtCl6 were obtained by the slow diffusion of an aqueous H2PtCl6 solution into a 4 M HCl solution of CB[6] during the course of 6 h. CB[6]·H2PtCl6 Crystallizes (
In the solid-state superstructure, the stoichiometry between CB[6] and [PtCl6]2− is 1:1, and [PtCl6]2− dianions interact (
We also mixed CB[6] with other platinum group metal anions, e.g., [PdCl4]2− dianions with square-planar geometry, [PdCl6]2− and [RhCl6]3− anions with regular-octahedral geometries. None of these three combinations—i.e., CB[6]− [PdCl4]2−, CB[6]− [PdCl6]2−, and CB[6]− [RhCl6]3 produced a precipitate (
Single-crystal X-ray diffraction analyses reveal (Table 2) that NH4 ions are absent in all the crystal structures. A possible explanation is that NH4 ions are replaced by protons in aqueous acidic solution during crystallization. This observation indicates that anions play a crucial role in the crystallization, while the effect of the NH4 ions is negligible. All the [PtCl4]2−, [PdCl4]2−, and [RhCl6]3− anions co-crystallize with CB[6], sustained (
The specific assembly and binding modes between CB[6] and the four anions are different. In the solid-state superstructures, CB[6]·[PtCl4]2− and CB[6]− [PdCl4]2− adopt (Table 2) the same space group, P21/c. The [MCl4]2− (M=Pt/Pd) dianions reside in (
The single-crystal X-ray diffraction analyses and DFT calculations performed on the four adducts formed between CB[6] molecules and the [PtCl6]2−, [PtCl4]2−, [PdCl4]2−, [RhCl6]3− anions led us to deduce possible factors for the promotion of rapid co-crystallization between CB[6] and the anions, including (i) highly specific intermolecular hydrogen bonds and ion-dipole interactions between the outer surface of CB[6] and the anions, which dominate the driving forces for forming the macrocycle-anion adducts and long-range ordered crystals, (ii) weak electrostatic repulsions between CB[6]− anion clusters, which favor the formation of bulk crystalline assemblies, and (iii) the low degrees of solvation of the resulting assemblies formed by these clusters, accelerating their precipitation from solution.
This selective co-crystallization between CB[6] and H2PtCl6 motivated us to test the validity of employing CB[6] for platinum separation. In an attempt to obtain an estimate of the co-precipitation efficiency, the suspension of the CB[6]·H2PtCl6 adduct was filtered, and the filtrate was subjected to inductively coupled plasma optical emission spectroscopic (ICP-OES) analysis in order to determine the concentration of [PtCl6]2− dianions remaining. On the basis of the initial and residual concentrations of these dianions in the aqueous solution, the yield of precipitated [PtCl6]2− can be obtained. The platinum-precipitation yield, based on the cocrystals of CB[6]·H2PtCl6, (
Three-way catalytic converters of vehicles,[41] containing considerable amounts of precious platinum, palladium, and rhodium metals, are vital components for converting the harmful nitrogen oxides (NOx), hydrocarbons, and carbon monoxide (CO) emitted from engines into relatively harmless nitrogen (N2) and carbon dioxide (CO2). With many vehicles reaching the end of their useful lives, a large number of waste catalytic converters are produced every year. From an economic as well as an environmental perspective, the recovery[42] of platinum from spent catalytic converters is vital. In order to test the potential of employing CB[6] as an extractant to separate platinum from spent three-way catalytic converters, we attempted to precipitate (
The Raman (
In an attempt to recover the platinum metal from the CB[6]·H2PtCl6 microcrystals, the adducts were dispersed in an aqueous solution, and adding N2H4·H2O, so as to reduce the [PtCl6]2− dianions down to platinum. After centrifuging and washing with aqueous acid solution to dissolve the residual CB[6], black platinum metal (
The process provide an alternative supramolecular based protocol for the recovery of platinum from platinum-bearing scrap.
We have shown that the instantaneous co-crystallization of CB[6] and H2PtCl6, which leads to rapid co-precipitation of the CB[6]·H2PtCl6 adduct, is sustained by multiple weak [Pt—Cl . . . H—C] hydrogen bonds and [Pt—Cl . . . C═O] ion-dipole interactions. This rapid co-crystallization and concomitant co-precipitation only occurs between CB[6] and H2PtCl6, despite the fact that similar outer surface interactions between CB[6] and other platinum group metal chloride anions are present. The selective recognition of [PtCl6]2− dianions through outer surface interactions with CB[6], not only expands the scope of the second-sphere coordination[29b, 32, 37c] of metal complexes on the part of cucurbituril, but also casts more light on the outer surface interactions by macrocycles. Additionally, this rapid co-precipitation between CB[6] molecules and [PtCl6]2− dianions can be applied to the extraction of platinum from aqueous solution. We have also demonstrated that CB[6] is able to separate selectively [PtCl6]2− dianions in the presence of [PdCl4]2− and [RhCl6]3− anions, and that the platinum metal can be recovered easily after reducing the co-precipitate with N2H4·H2O. This technology allows for the recovery platinum from the spent vehicular three-way catalytic converters as well as other platinum-bearing metal waste.
Unless otherwise specified or indicated by context, the terms “a”, “an”, and “the” mean “one or more.” For example, “a molecule” should be interpreted to mean “one or more molecules.”
As used herein, “about”, “approximately,” “substantially,” and “significantly” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which they are used. If there are uses of the term which are not clear to persons of ordinary skill in the art given the context in which it is used, “about” and “approximately” will mean plus or minus ≤10% of the particular term and “substantially” and “significantly” will mean plus or minus >10% of the particular term.
As used herein, the terms “include” and “including” have the same meaning as the terms “comprise” and “comprising.” The terms “comprise” and “comprising” should be interpreted as being “open” transitional terms that permit the inclusion of additional components further to those components recited in the claims. The terms “consist” and “consisting of” should be interpreted as being “closed” transitional terms that do not permit the inclusion additional components other than the components recited in the claims. The term “consisting essentially of” should be interpreted to be partially closed and allowing the inclusion only of additional components that do not fundamentally alter the nature of the claimed subject matter.
All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
Preferred aspects of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred aspects may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect a person having ordinary skill in the art to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein.
Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
All the chlorides, including H2PtCl6, (NH4)2PtCl6, (NH4)2PtCl4, cisplatin, transplatin, (NH4)2PdCl6, (NH4)2PdCl4, (NH4)3RhCl6, HCl (wt 37%) and N2H4·H2O (wt 78%) aqueous solutions were purchased from commercial suppliers and used without further purification unless stated otherwise. The cucurbit[6]uril was synthesized according to the previous literature with some modifications1. High purity water was generated by a Milli-Q.
Scanning electron microscopy (SEM) images were performed on a SU8030 scanning electron microscope at the voltages of 5.0/10 kV, while the energy-dispersive X-ray spectroscopy (EDS) elemental maps were recorded at 40 kV.
Raman spectra were performed on a HORIBA LabRAM HR Evolution Confocal Raman instrument. The system was equipped with a high spatial-resolution confocal microscope, a high performance Raman spectrometer multiple detectors, and used high-precision DuoScan imaging technology in order to enhance the measured S/N ratios and precision. The excitation light source in the measurements was a 785 nm laser, and the scan range was from 125 to 1000 cm−1.
Powder X-ray diffraction (PXRD) analyses were carried out on a STOE-STADI MP powder diffractometer equipped with an asymmetric curved Germanium monochromator (Cu-Kα1 radiation, λ=1.54056 Å) and a one-dimension silicon strip detector (MYTHEN2 1K from DECTRIS). Samples for structural analysis were measured at room temperature in transmission geometry. The simulated PXRD patterns were calculated using the Mercury software 4.3.0.
Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses were performed on a thermo iCap7600 ICP-OES (Thermo Fisher Scientific, Waltham, MA, USA) operating in radial view and equipped with a CETAC 520 autosampler (Omaha, NE, USA). The samples were filtered through a 0.45-μm filter. The filtrates were then diluted with ultrapure H2O and analyzed for the concentration of Pt, Pd, and Rh in comparison with standard solutions. Each sample was recorded using 5 sec visible exposure and 15 sec UV exposure time. Every sample was measured repeatedly for 3 times. The wavelengths selected for the analyses of the concentration of Pt were 203.646, 214.423, and 265.945 nm. The wavelengths selected for the analyses of the concentration of Pd were 324.270, 340.458, and 360.955 nm. The wavelengths selected for the analyses of the concentration of Rh were 339.682, 343.489, and 369.236 nm.
The X-ray photoelectron spectral (XPS) analyses were conducted on a fully digital state-of-the-art X-ray photoelectron spectrometer (Thermo Scientific ESCALAB 250Xi), which was equipped with an electron flood gun and a scanning ion gun. The diameter of X-ray spot was 500 μm, and the scan range was from 0 to 1200 eV.
Aqueous stock solutions of H2PtCl6, (NH4)2PtCl4, cisplatin, transplatin, (NH4)2PdCl6, (NH4)2PdCl4, (NH4)3RhCl6 were prepared by dissolving directly the corresponding commercially available complexes in high purity H2O, while aqueous solutions of CB[6] were prepared by dissolving CB[6] in an aqueous HCl (4 M) solution. When an CB[6] (1 mL, 10 mM) aqueous solution was added to the H2PtCl6, (NH4)2PtCl4, cisplatin, transplatin, (NH4)2PdCl6, (NH4)2PdCl4, (NH4)3RhCl6 aqueous solutions, respectively, a yellow suspension was formed specifically between CB[6] and H2PtCl6. The yellow solids were isolated by filtration, washing, and air-dried. The concentrations of [PtCl6]2−, [PdCl4]2−, and [RhCl6]3− remaining in the filtrates were determined by ICP-OES analysis. The metal precipitation yields were calculated based on the initial and residue concentrations of metal anions in the aqueous solution.
When an aqueous solution of CB[6] (1.0 mL, 10 mM) was mixed with equimolar amounts of [PtCl6]2−, [PdCl4]2− and [RhCl6]3− anions, a yellow suspension formed immediately. The yellow solid (116.7 mg,
(1) CB[6]·H2PtCl6
Effect of Changes in Concentration of CB[6]·H2PtCl6 on the Pt-Precipitation Yields
Effect of Changes in Concentration on the Pt/Pd/Rh-Precipitation Yields from Mixture
In order to gain a better understanding of the noncovalent bonding interactions and binding energies between CB[6] molecules and [PtCl6]2−, [PtCl4]2−, [PdCl4]2− and [RhCl6]3− anions, as well as the adjacent CB[6] molecules, density function theory (DFT) calculations have been carried out based on the crystal superstructures of CB[6]·H2PtCl6, CB[6]·H2PtCl4, CB[6]·H2PdCl4, and CB[6]·H3RhCl6.
The xyz coordinates for the single point calculations were extracted from the single-crystal X-ray crystallographic data of the four adducts. Single point calculations were performed with two levels of density functional theory (DFT) in the Orca program6 (version 4.1.2). (1) For the majority of binding energies, the hybrid Becke three-parameter Lee-Yang-Parr7 (B3LYP) functional, the Ahlrich's double zeta basis set with a polarization function8 Def2-SVP, Grimme's third generation dispersion with Beck Johnson damping (D3BJ), and an integration grid of 4 (Grid4) were used to evaluate the electronic energy. (2) For the binding energy of one anion with the nearest CB[6] neighbors computed as a single cluster, a lower less memory intensive level of pure Hartree-Fock with the Ahlrich's double zeta, reduced polarization functions basis Def2-SV(P), and default integration grid (Grid2) was used, without dispersion. In order to speed up the single point calculations with B3LYP, the Coulomb integral and numerical chain-of-sphere integration for the HF exchange9,10 (RIJCOSX) method was applied with the Def2/J auxiliary basis11 (AuxJ).
Visualization of Noncovalent Bonding Interactions Between CB[6] and H2PtCl6 in Solid-State Superstructure
Independent gradient model (IGM) analysis is an approach based on promolecular density—an electron density model prior to molecule formation—to identify and isolate intermolecular interactions. Strong polar attractions and van der Waals contacts are visualized as an iso-surface, respectively. Single crystal superstructures were used as input files. The binding surface was calculated using the Multiwfn 3.6 program through function 20 (visual study of weak interaction) and visualized by Chimera software.
This application claims priority to U.S. Patent Application Ser. No. 63/202,038, filed May 24, 2021, the contents of which are incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US22/30741 | 5/24/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63202038 | May 2021 | US |
