Electron Spin Echo Modulation Research Articles

Electron Spin Resonance and Electron Spin−Echo Modulation Studies of Synthesized NiAPSO-34 Molecular Sieve and Comparison with Ion-Exchanged NiH−SAPO-34 Molecular Sieve

The formation of monovalent nickel in NiAPSO-34 where nickel is believed to be incorporated into the framework of SAPO-34, and its interaction with several adsorbates are compared to Ni(I) species formed in NiH−SAPO-34, where Ni(II) is incorporated by solid-state ion exchange into known extraframework sites using electron spin resonance (ESR) and electron spin−echo modulation (ESEM) spectroscopies. Dehydration at temperatures above 573 K and hydrogen treatment at 573 K as well as γ-irradiation at 77 K produce one nickel species assigned by ESR as isolated Ni(I) in the two samples. Even though the ESR parameters of isolated Ni(I) species are similar after reduction, NiAPSO-34 and NiH−SAPO-34 show noticeable differences in their ESR characteristics after adsorption of various adsorbates, suggesting that Ni(I) in these two materials is in different sites. As a supplement to this, ESEM studies of 31P and 27Al, used to ascertain the location of the incorporated paramagnetic transition metal ion, also show significant differences in the modulation patterns. Simulation of the 31P modulation observed for NiH−SAPO-34 shows two nearest-neighbor phosphorus atoms at 3.9 Å and three next-nearest-neighbor phosphorus atoms at 6.5 Å, indicating that Ni(I) is at site II‘ in the chabazite cage near a six ring window after reduction. The 31P simulation for NiAPSO-34 shows three nearest-neighbor phosphorus atoms at a distance of 4 Å and two next-nearest-neighbor phosphorus atoms at 5.3 Å. This is consistent with Ni(I) ions substituting into a framework phosphorus site. In as-synthesized NiAPSO-34, the nickel ion is possibly also coordinated to additional waters to give distorted octahedral coordination. On dehydration, tetrahedrally coordinated nickel in a framework site of SAPO-34 is formed.

EPR and electron spin echo modulation spectroscopy of CrIII and CrV in CrAPSO-5 molecular sieve: Evidence for framework substitution

CrAPSO-5 molecular sieve was synthesized to incorporate CrIII into the molecular sieve framework using tripropylamine as a structure-directing agent. CrAPSO-5 was characterized by XRD, thermogravimetric analysis and IR spectroscopy. Treatment of as-synthesized CrAPSO-5 with a solution of CH3OH–HCl is effective in removing the tripropylamine. EPR shows CrIII with g1=5.20, g2=2.00 and g3=0.98, which is assigned to CrIII in a distorted octahedral coordination. Spectral simulation indicates a zero-field splitting parameter of 0.50 cm-1. CrIII in ion-exchanged (L)Cr-SAPO-5 also shows octahedral coordination and is located in the main channel. After dehydration, CrIII shows sharper EPR lines with g⊥=4.00 and g‖=2.00 which are assigned to CrIII in tetrahedral coordination. After calcination and dehydration, the EPR of CrAPSO-5 shows CrV in tetrahedral coordination, characterized by g⊥=1.97 and g‖=1.89. UV–VIS spectra support these coordination assignments. Electron spin echo modulation (ESEM) of 31P indicates that CrV substitutes for phosphorus in a framework site in calcined CrAPSO-5 and that CrV is in a six-ring window in dehydrated, oxidized (L)Cr-SAPO-5. Deuterium ESEM indicates, that, in CrAPSO-5, CrV interacts with one molecule of ethylene via a weak σ-bond, while in dehydrated, oxidized (L)Cr-SAPO-5, CrV interacts with one molecule of ethylene via a π-bond. These results seem consistent with framework substitution in a phosphorus site in CrAPSO-5.

Location of cupric ion and its adsorbate interactions in Cu(II)-exchanged mesoporous AlMCM-41 determined by electron spin resonance and electron spin echo modulation

The location of Cu(II) exchanged into mesoporous AlMCM-41 material and its interaction with various adsorbate molecules were reinvestigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. In contrast to previous work, it seems that Cu(II) is fully cordinated to adsorbates and interacts only with oxygen in an AlMCM-41 channel only in the absence of adsorbates. Cu(II) is octahedrally coordinated to six water molecules, as evidenced by an isotropic room temperature ESR signal. This species is located in an AlMCM-41 channel and rotates rapidly at room temperature. Evacuation at room temperature removes some of these water molecules, leaving the Cu(II) coordinated to fewer water molecules and anchored to oxygens in an AlMCM-41 channel wall. Adsorbate molecules such as water, methanol, ammonia, pyridine, aniline, acetonitrile, benzene and ethylene on dehydrated Cu-AlMCM-41 cause changes in the ESR spectrum of Cu(II), indicating complex formation with these adsorbates. Cu(II) forms a complex with six molecules of methanol, as evidenced by anisotropic room temperature ESR signal and ESEM data. Cu(II) also forms a square planar complex with four molecules of ammonia, pyridine and aniline, based on resolved nitrogen superhyperfine interaction and their ESR parameters. However, Cu(II) forms a complex with six molecules of acetonitrile, based on the ESR parameters. Only one molecule of benzene is directly coordinated to Cu(II). Only part of the Cu(II) coordinates weakly to one molecule of ethylene.

Location of cupric ion and its adsorbate interactions in Cu(II)-exchanged mesoporous AlMCM-41 determined by electron spin resonance and electron spin echo modulation

Location of cupric ion and its adsorbate interactions in Cu(II)-exchanged mesoporous AlMCM-41 determined by electron spin resonance and electron spin echo modulation

Reducibility and Adsorbate Interactions of Ti in Titanosilicate Molecular Sieve TS-1

Electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopy are used to study reducibility and adsorbate interaction of Ti in titanosilicate TS-1 molecular sieve. Various reduction methods were used to reduce Ti(IV) in TS-1 to Ti(III) which was then monitored by ESR. When TS-1, after dehydration and oxygen treatment at high temperature followed by evacuation (activation), is γ-irradiated at 77 K; an ESR signal withg‖=1.970 andg⊥=1.906 is observed for isolated Ti(III) centers. Radiation induced defect centers known as V centers are also observed after γ-irradiation. When activated TS-1 is treated with CO or H2at 673 K, an axial ESR signal withg⊥=1.968 andg‖=1.933 is observed which is suggested to be Ti(III)(CO)nand Ti(III)(H2)ncomplexes. When activated TS-1 is exposed to D2O at room temperature and subsequently γ-irradiated at 77 K, a new ESR signal withg=1.924 is observed. This species is identified as Ti(III)-(OD)1from2D ESEM data. Adsorption of CH3OD on activated TS-1 produces a new Ti(III) species withg=1.931. This species is identified as Ti(III)-(CH3OD)1from2D ESEM data. Adsorption of C2D4on activated TS-1 produces a new Ti(III) species withg⊥=1.968 andg‖=1.910. This species is identified as Ti(III)-(C2D4)1from2D ESEM data. Possible coordination geometries of the various Ti(III)-adsorbate complexes are discussed.

Evaluation of relative catalytic activities of Cu(II)-exchanged L, offretite and omega gallosilicates based on Cu(II) location and adsorbate interactions determined by CW and pulsed electron spin resonance

Three structurally related gallosilicates with L, offretite and omega zeolite structures were synthesized and cupric ion was ion-exchanged into each of these gallosilicates. The location of Cu(II) and its interaction with adsorbates in these Cu(II)-exchanged gallosilicates have been studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. In fresh hydrated state, Cu(II) is located in a main channel for these materials but with different coordination numbers to water. Cu(II) is octahedrally coordinated to six water molecules in L, while Cu(II) is coordinated to three water molecules and to framework oxygens in the main channel in offretite and omega. During evacuation at increasing temperature, Cu(II) moves from the main channel towards recessed sites. Dehydration produces predominantly one Cu(II) species located in recessed sites such as hexagonal prism for L and offertite and six-ring window of a gmelinite cage for omega based on a lack of broadening of its ESR lines by added oxygen. In L and offretite gallosilicates, there is evidence for back migration of Cu(II) from a hexagonal prism into a main channel to coordinate with adsorbates. Cu(II) in L gallosilicate forms complexes with bigger molecules such as benzene, pyridine and aniline. However, no complex formation between Cu(II) and each of these bulky molecules was observed due to a distorted 12-ring entrance in offretite which makes diffusion of these bulky molecules into the main channel difficult. In omega, the back migration of Cu(II) from a gmelinite cage to a main channel was blocked and thus coordination was possible only with small molecules which can diffuse into the gmelinite cage. The L structure is likely to be the best and comparable to ZSM-5 zeolite, offretite the next and omega the least good for catalytic efficiency for exchanged transition metal ions.

Electron Magnetic Resonance Study on the Mobility of Nitroxide Spin Probes in the Dipalmitoylphosphatidylcholine Lipid Bilayers: Effect of Poly(ethylene glycol)

The degree of interaction of the lipid bilayer of a dipalmitoylphosphatidylcholine (DPPC) vesicle with poly(ethylene glycol) (PEG) was studied by determining electron spin resonance (ESR) line widths of nitroxide spin probes and measuring interaction distances between nitroxide groups in the hydrophobic core region and interface water (D 2 O) with electron spin-echo modulation (ESEM). The increasing ESR line width with increasing concentration of PEG up to 10 mM indicates that the PEG intercalates between the headgroups of the DPPC vesicle due to hydrophobic interaction with surfactant alkyl chains. This action ofPEG is also reflected in increased deuterium modulation depths of the ESEM spectra. Thereafter, some interface water (D 2 O) is replaced by PEG molecules with increasing concentration of PEG at DPPC interface. This interpretation is supported by the decreased deuterium modulation depth up to 10 mM of PEG and slightly decreased deuterium modulation depth thereafter.

ESR and ESEM studies of Mn-containing MCM-41 materials

Abstract Through electron spin resonance (ESR) and electron spin echo modulation (ESEM) studies, three Mn(II) species are found in three kinds of Mn-containing MCM-41 materials: ion-exchanged Mn-MCM-41, synthesized MnMCM-41 and synthesized MnMCM-41(Ca) with subsequent CaCl 2 exchange. Mn(II) species I with a well-resolved sextet centered at g =2.007 has distorted octahedral symmetry and is observed in hydrated ion-exchanged Mn-MCM-41 and in synthesized calcined MnMCM-41. Mn(II) species II with g =5.2 and 3.2 is observed in dehydrated Mn-MCM-41 and MnMCM-41; attributed to zero field interactions. Both species I and II correspond to extra-framework Mn(II). Mn(II) species III, with a symmetric line at g =2.004 and a broad line-width of 250 to 350 G is assigned to framework sites. Extra-framework Mn(II) species I and II coordinate with four D 2 O and are accessible to water, but framework Mn(II) species III coordinates with only three D 2 O and is less accessible to water.

Electron Spin Resonance and Electron Spin Echo Modulation Studies on Reducibility, Location, and Adsorbate Interactions of Ni(I) in Ni(II)-Exchanged SAPO-34

Electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies were used to study the reducibility, location, and adsorbate interactions of Ni(I) in NiH−SAPO-34, in which Ni(II) was introduced into extraframework sites of SAPO-34 by partial ion exchange of H(I) by Ni(II). After dehydration at temperatures above 573 K as well as after γ-irradiation at 77 K, one nickel species assigned as isolated Ni(I) by ESR is observed. Along with the isolated Ni(I) species, a second species assigned to Ni(I)−(H2)n is also observed after hydrogen reduction at 573 K. Adsorption of water into reduced NiH−SAPO-34 forms an axially symmetric Ni(I)−(O2)n complex indicating water decomposition by Ni(I). Adsorption of methanol into reduced NiH−SAPO-34 forms two Ni(I)-methanol complexes suggested to be located at two different sites in the chabazite structure. Similarly, two Ni(I)−(C2D4)n complexes, the predominant one exhibiting axial symmetry and the other one having rhombic symmetry, are formed after eth...

SAPO-35 Molecular Sieve: Synthesis, Characterization, and Adsorbate Interactions of Cu(II) in CuH−SAPO-35

Synthesis of small-pore silicoaluminophosphate SAPO-35 (structurally analogous to the zeolite levyne) using hexamethyleneimine in aqueous and fluoride media is described for the first time. Pure, highly crystalline samples of SAPO-35 were obtained within a short reaction period of 24 h. Various factors affecting crystallinity and phase purity of SAPO-35 were studied. Samples were characterized by X-ray powder diffraction, 27Al, 29Si and 31P solid state MAS NMR spectroscopy, FTIR spectroscopy, thermal analysis (TG and DTA), surface area measurement, electron microprobe analysis and scanning electron microscopy. SAPO-35 crystallizes with highly uniform rhombic crystals about 1 μm across. Two crystallographically distinct tetrahedral framework sites in SAPO-35 are shown from MAS NMR studies. 29Si MAS NMR spectra show that silicon substitutes for framework phosphorus and generates large Bronsted acidity. The location of Cu(II) ions exchanged into H−SAPO-35 and their interaction with deuterated water, ammonia, methanol, and ethylene have been investigated by electron spin resonance (ESR) and electron spin−echo modulation (ESEM) techniques. Simulation parameters of the 31P ESEM spectrum suggest that the hydrated Cu(II) complex, i.e., CuII(H2O)6, is located in the levyne cage. During dehydration some of the Cu(II) ions may migrate into double hexagonal prisms. Room-temperature adsorption of D2O on CuH−SAPO-35 after dehydration at 723 K and subsequent O2 treatment and evacuation at the same temperature (activation) forms a Cu(II)−aquo complex with axially symmetric ESR parameters (g∥ = 2.387 and A∥ = 0.0151 cm-1). This complex is suggested to be CuII(D2O)3 based on 2D ESEM data. Adsorption of ND3 on activated CuH−SAPO-35 produces two CuII(ND3)n complexes with axially symmetric ESR parameters. When CD3OH is adsorbed on CuH−SAPO-35, the resultant Cu(II) complex with ESR parameters g∥ = 2.398 and A∥ = 0.0142 cm-1 contains one methanol molecule coordinating directly with the metal ion based on 2D ESEM measurements. Adsorption of C2D4 on activated CuH−SAPO-35 gives two CuII(C2D4)n complexes based on ESR measurements.

Synthesis and Characterization of CuAPO-5 Molecular Sieves: Evidence for the Framework Incorporation of Cu(II) Ions

The hydrothermal synthesis of CuAPO-5 molecular sieves has been investigated by using Cu(II) oxide in the presence of tetraethylammonium hydroxide as a template. The CuAPO-5 material was characterized by X-ray powder diffraction, FT-IR spectroscopy, scanning electron microscopy, and elemental analysis. Supporting evidence for the framework location of copper was obtained from electron spin resonance and electron spin-echo modulation spectroscopy experiments.

Quenching of excited states of pyrene derivatives by amphiphilic nitroxide radicals in cationic micellar solutions. Dynamics and location of the guest molecules in the aggregates

Steady-state and nanosecond time-resolved studies have been performed on fluorescence quenching of excited pyrene sulfonic acid and pyrene butyric acid (PBA and PSA, respectively, in the form of sodium salts) by n-doxylstearic methyl esters ( n-DSE, n=5, 10, 12) in aqueous solution of cationic micelles of hexadecyltrimethylammonium chloride (HTAC, 0.1 M). The results are compared with those reported earlier for pyrene (P) as a luminophore (Szajdzinska-Pietek and Wolszczak, Chem. Phys. Lett., 270 (1997) 527). It is shown that PBA/ n-DSE and PSA/ n-DSE luminophore/quencher pairs, unlike P/ n-DSE pairs, are not suitable for determination of the micellar aggregation number, neither by the ‘quasi-static’ method of Turro—Yekta nor by the dynamic method of Infelt—Tachiya. It is suggested that the fluorescence decay curves in the examined systems can be adequately described in terms of dispersive kinetics using the time-dependent rate coefficient for intramicellar quenching process. The average location of the luminophore and the quencher molecules in the aggregates is discussed, considering previous findings of electron spin echo modulation studies of n-doxylstearic acid spin probes in micellar systems.

Photoinduced electron transfer from alkylpyrenes embedded into DHP, DPPC and DODAC vesicles studied with electron paramagnetic resonance and electron spin echo modulation spectroscopies

Photoinduced electron transfer from alkylpyrene derivatives solubilized in cationic dioctadecyldimethylammonium chloride (DODAC), neutral dipalmitoylphosphatidylcholine (DPPC) and anionic dihexadecylphosphate (DHP) vesicles to interface water (D2O) was monitored by changing the pendant alkyl chain length of the alkylpyrenes and the interface charge of the vesicles. The amount of photoproduced pyrene cation radical defined as the photoyield decreased with increasing alkyl chain length of the alkylpyrene and with the interface charge from cationic DODAC to neutral DPPC to anionic DHP vesicles. The interpretation is that the increased alkyl chain length of alkylpyrene increases the electron transfer distance between the pyrene moiety as an electron donor and the interface water (D2O) as an electron acceptor. This occurs by deeper penetration of the alkylpyrene into the hydrophobic region of the vesicles for longer alkyl chains due to greater hydrophobic interaction of the alkylpyrene with the surfactant alkyl chains. This interpretation is supported by a decreasing deuterium modulation depth trend. The decreasing photoyields of alkylpyrene from DODAC to DPPC to DHP vesicles are due to an increasing energy barrier for electron transfer through the vesicular interface.

Electron spin-echo modulation spectroscopic study of the type I copper center associated with stellacyanin from Rhus verniciferaExamination of the graphical analysis of ESEEM spectra for two dissimilar weakly coupled 14Nnuclei

Download options Please wait... Article information DOI https://doi.org/10.1039/A706120J Article type Paper Download Citation J. Chem. Soc., Faraday Trans., 1998,94, 375-386 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Electron spin-echo modulation spectroscopic study of the type I copper center associated with stellacyanin from Rhusvernicifera C. J. Bender and J. Peisach, J. Chem. Soc., Faraday Trans., 1998, 94, 375 DOI: 10.1039/A706120J To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Christopher J. Bender Jack Peisach

Electron Spin Resonance and Electron Spin Echo Modulation Spectroscopic Studies of Chromium Ion Location and Adsorbate Interactions in Calcined CrAPSO-11

The local environment of the chromium ion in calcined CrAPSO-11, which may involve framework sites, is compared with the Cr ion environment in solid-state ion-exchanged (S)Cr−SAPO-11 which involves ion exchange into nonframework sites at high temperature. Powder X-ray diffraction confirms that CrAPSO-11 has the SAPO-11 framework and is highly crystalline. The 27Al and 29Si magic-angle-spinning nuclear magnetic resonance spectra are similar to those of corresponding SAPO-11 showing only one type of tetrahedral atom. As-synthesized CrAPSO-11 shows an ESR spectrum assignable to Cr(III), but on calcination this converts to Cr(V). (S)Cr−SAPO-11 forms Cr(V) directly since solid-state ion exchange occurs at high temperature. The UV−vis spectrum of calcined, hydrated CrAPSO-11 is assigned to Cr(V), and after dehydration the coordination for Cr(V) seems consistent with tetrahedral as expected for a framework site. Electron spin resonance (ESR) of calcined, hydrated CrAPSO-11 shows Cr(V) which is consistent with sq...

Electron spin resonance and electron spin echo modulation studies of Cu(II) cation locations and adsorbate interactions in ionexchanged Cu-MCM-22 zeolite

MCM-22 is a medium-pore high-silica-containing zeolite. Its unique structure contains two noninterconnected channel systems with potential for transition metal-based heterogeneous catalysis. Paramagnetic Cu(II) cation is ionexchanged into MCM-22 to act as a probe for electron spin resonance and electron spin echo modulation spectroscopic methods to verify the location of the ion-exchangeable sites. The electron spin resonance spectra of dehydrated Cu-MCM-22 are strikingly well-resolved and exhibit features related to both 63Cu and 65Cu nuclei. Interactions with water, ammonia, methanol, pyridine, benzene, cyclohexylamine and triethylamine adsorbed on Cu-MCM-22 are studied. Three types of ion-exchangeable extra framework site are identified.

Electron Spin Resonance and Electron Spin Echo Modulation Evidence for the Isomorphous Substitution of Ti in TAPO-5 Molecular Sieve

New evidence for the isomorphous substitution of titanium into titanium aluminophosphate molecular sieve of structure type AFI (TAPO-5) is reported by combined electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopic studies. Synthesized TAPO-5 and TiO2/SAPO-5 materials are compared. These materials were activated and then reduced by γ-irradiation at 77 K or by CO at ambient to high temperatures. γ-irradiation at 77 K of TAPO-5 produces an ESR signal characterized by g1 = 1.965, g2 = 1.920, and g3 = 1.879 best explained as arising from trivalent titanium at a framework site together with a strong signal due to V centers. γ-irradiation of TiO2/SAPO-5 gives an ESR signal with g⊥ = 1.971 and g∥ = 1.907 typical of Ti(III) in octahedral symmetry. Upon CO reduction TAPO-5 gives a spectrum with rhombic g parameters g1 = 1.969, g2 = 1.954, and g3 = 1.923, which are different from the corresponding parameters of the Ti(III) species produced by γ-irradiation. CO reduction of TiO2/SAPO-5 ...

Cupric Ion Location and Adsorbate Interactions in Cu(II) Exchanged Erionite-like SAPO-17 Molecular Sieve

Erionite-like silicoaluminophosphate molecular sieve SAPO-17 has been synthesized using cyclohexylamine as the organic structure directing molecule. The location of Cu(II) ions exchanged into H-SAPO-17 and the interaction of Cu(II) ions with water, ammonia, methanol, and ethylene have been investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) techniques. Simulation parameters of the 31P ESEM spectrum suggest that the hydrated Cu(II) complex, CuII(H2O)6, is located in the erionite supercage. During dehydration some of the bare Cu(II) ions migrate into the smaller cancrinite cage. Room temperature adsorption of D2O on CuH-SAPO-17 after dehydration at 723 K and subsequent O2 treatment and evacuation at the same temperature (activation) forms a Cu−aquo complex with axially symmetric ESR parameters (g|| = 2.391 and A|| = 0.0142 cm-1). This complex is suggested to be CuII(D2O)3 based on 2D ESEM data. Adsorption of ND3 on activated CuH-SAPO-17 produces CuII(ND3)3 with axially sym...

Cross peak intensities in two-dimensional four-pulse electron spin echo modulation spectra of deuteriums in single crystals

The intensities of the cross peaks in two-dimensional deuterium four-pulse electron spin echo envelope modulation spectra of single crystals have been calculated by a first order approximation for two limiting cases where the deuterium hyperfine interactions is small or large with respect to the deuterium nuclear Larmor frequency. The analysis shows that four out of the eight possible cross peaks of the single quantum transitions have intensities linearly proportional to the modulation depth parameter in both limits. The intensities of the other four cross peaks together with the cross peaks of the double quantum transitions are proportional to higher order in the modulation depth parameter. Therefore, only four deuterium peaks will be observed in many experimental cases leading to a simplification of the two-dimensional four-pulse electron spin echo envelope modulation spectra. The presented analysis is supported by experimental spectra of two different single crystals and by simulations based on an exact diagonalization of the spin Hamiltonian. The impact of the simplification of the deuterium spectra on investigations in disordered systems is briefly outlined.

Electron Spin Resonance and Electron Spin Echo Modulation Spectroscopic Studies of Cupric Ion−Adsorbate Interactions in Synthetic Clinoptilolite

The site locations and adsorbate interactions of Cu2+ in Cu2+-exchanged synthetic clinoptilolite have been determined by electron spin resonance and electron spin echo modulation spectroscopies. Strong effects of the H+, Li+, Na+, and K+ cocations have been found on the coordination number and on the location of the cupric ion. Cu2+ coordinates three molecules of water in hydrated CuH−clinoptilolite (CuH−Clino) and in CuLi−Clino, but only two molecules of water in hydrated CuNa−Clino and CuK−Clino. Two cupric ion sites are observed in many cases and are attributed to sites in ten-ring and eight-ring main channels. Activation to 400 °C is sufficient to remove these water molecules and cause migration of Cu2+ to an eight-ring intersecting channel. Adsorption of polar molecules such as water, ammonia, alcohols, and acetonitrile causes the migration of Cu2+ into the main channels to coordinate with the adsorbates. Cu2+ forms complexes with three molecules of ethanol and four of ammonia in CuH−Clino, but only coordinates to two molecules of ethanol or methanol and three of ammonia in CuNa−Clino, and to one molecule of ethanol or methanol and three of ammonia in CuK−Clino. Cu2+ coordinates four molecules of acetonitrile at the center of a main channel in clinoptilolite, and this coordination number is unaffected by the alkali metal cocations.