Stability of Iodine Species Trapped in Titanium-Based MOFs: MIL-125 and MIL-125_NH2.

Two titanium-based MOFs MIL-125 and MIL-125_NH2 are synthesized and characterized using high-temperature powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), N2 sorption, Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), and electron paramagnetic resonance (EPR). Stable up to 300 °C, both compounds exhibited similar specific surface areas (SSA) values (1207 and 1099 m2 g-1 for MIL-125 and MIL-125_NH2, respectively). EPR signals of Ti3+ are observed in both, whith MIL-125_NH2 also showing ─NH2 ●+ signatures. Both MOFs efficiently adsorbed iodine in continuous gas flow over five days, with MIL-125 trapping 1.9 g.g-1 and MIL-125_NH2 trapping 1.6 g.g-1. MIL-125_NH2 exhibited faster adsorption kinetics due to its smaller band gap (2.5 against 3.6 eV). In situ Raman spectroscopy conducted during iodine adsorption revealed signal evolution from "free" I2 to "perturbed" I2, and I3 -. TGA and in situ Raman desorption experiments showed that ─NH2 groups improved the stabilization of I3 - due to an electrostatic interaction with NH2 ●+BDC radicals. The Albery model indicated longer lifetimes for iodine desorption in I2@MIL-125_NH2, attributed to a rate-limiting step due to stronger interaction between the anionic iodine species and the ─NH2 ●+ radicals. This study underscores how MOFs with efficient charge separation and hole-stabilizer functional groups enhance iodine stability at higher temperatures.

Acidity: A Key Parameter in Zeolite-Templated Carbon Formation.

This work reveals the crucial role of zeolite acidity in the synthesis of zeolite-templated carbons (ZTCs). While textural and chemical properties appear to be independent from acidity at a given synthesis temperature, the spin concentration in hybrid materials appears to be strongly impacted by the zeolite acid site concentration. The electrical conductivity of the hybrids and resulting ZTCs are closely related to the spin concentration in the hybrid materials. The amount of zeolite acid sites hence fundamentally impacts the electrical conductivity of the samples that spans over a range of four magnitudes. Electrical conductivity reveals as key parameter to describe the quality of ZTCs.

Capture of Gaseous Iodine in Isoreticular Zirconium-Based UiO-n Metal-Organic Frameworks: Influence of Amino Functionalization, DFT Calculations, Raman and EPR Spectroscopic Investigation.

A series of Zr-based UiO-n MOF materials (n=66, 67, 68) have been studied for iodine capture. Gaseous iodine adsorption was collected kinetically from a home-made set-up allowing the continuous measurement of iodine content trapped within UiO-n compounds, with organic functionalities (-H, -CH3 , -Cl, -Br, -(OH)2 , -NO2 , -NH2 , (-NH2 )2 , -CH2 NH2 ) by in-situ UV-Vis spectroscopy. This study emphasizes the role of the amino groups attached to the aromatic rings of the ligands connecting the {Zr6 O4 (OH)4 } brick. In particular, the preferential interaction of iodine with lone-pair groups, such as amino functions, has been experimentally observed and is also based on DFT calculations. Indeed, higher iodine contents were systematically measured for amino-functionalized UiO-66 or UiO-67, compared to the pristine material (up to 1211 mg/g for UiO-67-(NH2 )2 ). However, DFT calculations revealed the highest computed interaction energies for alkylamine groups (-CH2 NH2 ) in UiO-67 (-128.5 kJ/mol for the octahedral cavity), and pointed out the influence of this specific functionality compared with that of an aromatic amine. The encapsulation of iodine within the pore system of UiO-n materials and their amino-derivatives has been analyzed by UV-Vis and Raman spectroscopy. We showed that a systematic conversion of molecular iodine (I2 ) species into anionic I- ones, stabilized as I- ⋅⋅⋅I2 or I3 - complexes within the MOF cavities, occurs when I2 @UiO-n samples are left in ambient light.

Electron transfers in graphitized HZSM-5 zeolites.

In the present work, we report the electron transfers occurring after ionization of the guest molecules of t-stilbene incorporated in graphitized HZSM-5 zeolites and we compare these results with the data obtained previously for graphite-free zeolites. Complementary diffuse reflectance UV-vis and Raman scattering spectroscopies provide evidence for stabilization of long lived charge separated states as observed in non-graphitized ZSM-5. The spectral features indicate that these species are located in the channels of the zeolite structure. However, the pulsed EPR technique shows strong coupling between unpaired electrons and the 13C atoms in the case of graphitized zeolites while this interaction is not observed in normal zeolites. This is assigned to the presence of charge transfer complexes in the close vicinity of graphite areas and to the possible electron transfer to the graphitized domain. Using cyclic voltammetry, an electrochemical response is observed for the first time in such systems demonstrating the role played by graphite in the electron transfers.

Determination of Electronic Recombination Free Energy in Zeolites: Effects of the Charge Balancing Cation and Confinement.

The adsorption of DPH in M6.6 ZSM-5 (M=Na+ , K+ , Rb+ , Cs+ ), RbFER and RbMOR channel zeolites takes place without chemical or structural modification. After photoexcitation of these systems, a radical cation-electron pair is observed and has a sufficiently long lifetime to be studied by diffuse reflectance UV-visible spectroscopy. The study of the recombination of this radical cation-electron pair was carried out at different temperatures and allowed the determination of the activation energy as a function of the nature of the charge-balancing cation but also of the confinement effect. It appears that the activation energy decreases progressively from Na+ to Cs+ but also when the confinement decreases. To go further, the free enthalpies have been calculated from the Marcus theory demonstrating experimentally that these systems are located in the inverted Marcus region.

Effect of zeolite morphology on charge separated states: ZSM-5-type nanocrystals, nanosheets and nanosponges.

In the present work, we investigate the electron transfer occurring in the porous void of three MFI-type zeolite (ZSM-5) nanomaterials (nanocrystals, nanosheets and nanosponges) after adsorption and photoexcitation of t-stilbene (t-St). ZSM-5 nanosheets are constituted of lamellar stacking of several nanosheets (20-40 nm) where each nanosheet has a thickness of 2 nm. Nanosponges are composed of ZSM-5 nanocrystals (2-3 nm) separated by mesoporous holes of 5.8 nm facilitating the synthesis of hierachical materials. While the nanosheets show microporosity similar to that observed for the ZSM-5 nanocrystals, the absorption isotherms of the nanosponges show the existence of secondary micropores. After photoirradiation of t-St, UV-vis absorption spectroscopy shows the formation of charge separated states (radical cation and charge transfer complex) in the nanocrystals and in the nanosheets whereas no ionized species is detected in the nanosponges. The radical cation (RC) is stabilized in the nanosheets while it evolves very rapidly towards a Charge Transfer Complex (CTC) in the nanocrocrystals. The particular morphology of the nanosheets and nanosponges is put forward to explain this result since all host materials are of the MFI-type. To investigate ultra-short phenomena in the three nanomaterials, the UV-vis transient spectra were recorded between 2 and 450 µs after photoexcitation by nanosecond laser pulses. In the nanocrystals and nanosheets only the RC is detected whereas CTC formation is not observed. Photoexcitation of t-St in the nanosponges also leads to the formation of a RC but it recombines completely within 70 µs. This suggests the preferential location of t-St in the secondary micropores with pores larger than the micropores of the MFI-type framework and possibly in the mesopores of the nanosponges.

Uranyl Cation Incorporation in the [P8W48O184]40- Macrocycle Phosphopolytungstate.

Association of uranyl nitrate with the macrocycle [P8W48O184]40- in formate buffered aqueous solution leads to the formation of a new compound (K11.3Li8.1Na22)[(UO2)7.2(HCOO)7.8(P8W48O184)Cl8]·89H2O (1). Its characterization by XRD reveals a high disorder of the uranyl cations and the formation of monodimensional chains of anionic [(UO2)7.2(HCOO)7.8(P8W48O184)Cl8]41.4- entities linked through formate ligands. The uranyl species are located either in the coordinating sites of the macrocycle [P8W48O184]40- or at its surface. Further studies of the molecule by SAXS and TEM show that the 1D chain collapses to give rise to the formation of polydisperse spherically aggregated species with an average radius of 129 Å.

A Spectroscopic Study of Tautomeric Equilibrium of Salicylideneaniline in ZSM-5 Zeolites.

Salicylideneaniline (SA) sorbed in cation-exchanged M-ZSM-5 (M = H⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺ and Zn2+) zeolites was studied by spectroscopic techniques assisted by quantum-chemical calculations. The nature of extra-framework cations present in the zeolite void was found to affect the spectral signature of the sorbed SA molecule that points to the shift of tautomeric equilibrium between the enol and keto forms. Small size cations, such as H⁺ and Li⁺, stabilize a cis-keto SA tautomer along with a enol one in the zeolite structure. The calculations indicate that the sorbed cis-keto tautomer may have the dipole large enough to be considered as a zwitterion. New features appearing in the spectra with the increase of the cation size were attributed to the presence of trans-keto SA tautomer, which up to now has been observed only in time-resolved spectroscopic experiments. A strong interaction of the molecule with cations in Zn-ZSM-5 zeolite results in the chelation of enol SA with the divalent Zn2+ ions. The results of the study suggest that the tautomeric equilibrium of molecules belonging to the Schiff base family can be tuned by the confinement in the nanoporous materials via a choice of topology of zeolite framework and the nature of extra-framework cations.

Vibrational dynamics of the salicylideneaniline molecule in the solid phase and the confined state.

The salicylideneaniline (SA) molecule, both in the solid phase and sorbed in silicalite-1 zeolite, was studied by a large palette of vibrational spectroscopic methods (INS, Raman, and infrared) and by computational techniques. The comparison of the experimental and calculated spectra unambiguously indicates that the molecule is present in the cis-enol form in both phases. The results of the study allowed the proposal of a complete assignment of the vibrational spectrum of the SA molecule. The analysis of peak positions in the Raman and INS spectra of the molecule in the solid and sorbed states, and of the corresponding vibrational modes, shows that the confinement by the zeolite mostly affects those modes whose vibrational amplitude is localized on atoms of the phenol ring. This finding suggests that the molecule sits in the zeolite void such that the phenol ring is affected by the sorption to a greater extent than the benzene one. This assumption is corroborated by results of molecular modeling that shows the most energetically preferred position of the molecule in the straight channel of the zeolite framework with the phenol ring lying between two channel intersections, whereas the benzene ring is situated in the intersection.

Electron-Donor Functional Groups, Band Gap Tailoring, and Efficient Charge Separation: Three Keys To Improve the Gaseous Iodine Uptake in MOF Materials.

Metal-organic frameworks (MOFs) have been largely investigated worldwide for their use in the capture of radioactive iodine due to its potential release during nuclear accident events and reprocessing of nuclear fuel. The present work deals with the capture of gaseous I2 under a continuous flow and its subsequent transformation into I3- within the porous structures of three distinct, yet structurally related, terephthalate-based MOFs: MIL-125(Ti), MIL-125(Ti)_NH2, and CAU-1(Al)_NH2. The synthesized materials exhibited specific surface areas (SSAs) with similar order of magnitude: 1207, 1099, and 1110 m2 g-1 for MIL-125(Ti), MIL-125(Ti)_NH2, and CAU-1(Al)_NH2, respectively. Because of that, it was possible to evaluate the influence of other variables over the iodine uptake capacity─such as band gap energies, functional groups, and charge transfer complexes (CTC). After 72 h of contact with the I2 gas flow, MIL-125(Ti)_NH2 was able to trap 11.0 mol mol-1 of I2, followed by MIL-125(Ti) (8.7 mol mol-1), and by CAU-1(Al)_NH2 (4.2 mol mol-1). The enhanced ability to retain I2 in the MIL-125(Ti)_NH2 was associated with a combined effect between its amino group (which has a great affinity toward iodine), its smaller band gap (2.5 eV against 2.6 and 3.8 eV for CAU-1(Al)_NH2 and MIL-125(Ti), respectively), and its efficient charge separation. In fact, the presence of a linker-to-metal charge transfer (LMCT) mechanism in MIL-125(Ti) compounds separates the photogenerated electrons and holes into the two distinct moieties of the MOF: the organic linker (which stabilizes the holes) and the oxy/hydroxy inorganic cluster (which stabilizes the electrons). This effect was observed using EPR spectroscopy, whereas the reduction of the Ti4+ cations into the paramagnetic Ti3+ species was evidenced after irradiation of the pristine Ti-based MOFs with UV light (<420 nm). In contrast, because CAU-1(Al)_NH2 exhibits a purely linker-based transition (LBT)─with no EPR signals related to Al paramagnetic species─it tends to exhibit faster recombination of the photogenerated charge carriers as, in this case, both electrons and holes are located over the organic linker. Furthermore, the transformation of the gaseous I2 into In- [n = 5, 7, 9, ...] intermediates and then into I3- species was evaluated using Raman spectroscopy by following the evolution of their respective bands at about 198, 180, and 113 cm-1. This conversion─which is favored by an effective charge separation and smaller band gaps─increases the I2 uptake capacity of the compounds by creating specific adsorption sites for these anionic species. In fact, because the -NH2 groups act as an antenna to stabilize the photogenerated holes, both In- and I3- are adsorbed into the organic linker via an electrostatic interaction with these positively charged entities. Finally, changes regarding the EPR spectra before and after the iodine loading were considered to propose a mechanism for the electron transfer from the MOFs structure to the I2 molecules considering their different characteristics.

Degradation mechanisms of organic compounds in molten hydroxide salts: a radical reaction yielding H2 and graphite.

Molten salts are used in various waste treatments, such as recycling, recovery or making inert. Here, we present a study of the degradation mechanisms of organic compounds in molten hydroxide salts. Molten salt oxidation (MSO) using carbonates, hydroxides and chlorides is known for the treatment of hazardous waste, organic material or metal recovery. This process is described as an oxidation reaction due to the consumption of O2 and formation of H2O and CO2. We have treated various organic products, carboxylic acids, polyethylene and neoprene with molten hydroxides at 400 °C. However, the reaction products obtained in these salts, especially carbon graphite and H2 without CO2 emission, challenges the previous mechanisms described for the MSO process. Combining several analyses of the solid residues and the gas produced during the reaction of organic compounds in molten hydroxides (NaOH-KOH), we demonstrate that these mechanisms are radical-based instead of oxidative. We also show that the obtained end products are highly recoverable graphite and H2, which opens a new way of recycling plastic residues.

Spontaneous ionization of N-alkylphenothiazine molecules adsorbed in channel-type zeolites: effects of alkyl chain length and confinement on electron transfer.

The mere mixing of N-alkylphenothiazines with three channel-type acid zeolites with various structures (ferrierite, H-MFI, and mordenite) induces the spontaneous ionization of the heterocyclic molecule in high yield upon adsorption. The diffuse reflectance UV-visible absorption and Raman scattering spectra show that the accessibility of the highly polarizing acid sites is not indispensable to induce the spontaneous ionization process. Due to their particularly low ionization potential values (6.7 eV), the adsorption of the molecules on the external surface or in the inner volume is the key parameter to generate the radical cation. However, the ionization yield and charge stabilization are intimately correlated to the possibility of the zeolites accommodating molecules inside their channels. Moreover, the higher electrostatic field gradient induced by high confinement is required to favor the second ionization and dication formation. The alkyl chain length plays a decisive role by either slowing down the diffusion process or blocking the molecule at the pore entry. Therefore, the efficiency of the ionization process that depends on the number of adsorbed molecules decreases significantly from phenothiazine to the N-alkylphenothiazines. The spectral data demonstrate that deformation of the alkyl group is necessary to allow the diffusion of the molecules into the channels.

Photoinduced electron transfers in zeolites: impact of the aluminum content on the activation energies.

We report the activation energy determination corresponding to the recombination of the radical cation electron moiety created through photoionization of the 1,6-diphenyl-1,3,5-hexatriene molecule incorporated in ZSM-5 zeolite channels. We demonstrate that the charge separated state stabilization in zeolite does not depend only on the Al content but also on the Al repartition.

Iodine Uptake by Zr-/Hf-Based UiO-66 Materials: The Influence of Metal Substitution on Iodine Evolution.

Many works reported the encapsulation of iodine in metal-organic frameworks as well as the I2 → I3- chemical conversion. This transformation has been examined by adsorbing gaseous iodine on a series of UiO-66 materials and the different Hf/Zr metal ratios (0-100% Hf) were evaluated during the evolution of I2 into I3-. The influence of the hafnium content on the UiO-66 structure was highlighted by PXRD, SEM images, and gas sorption tests. The UiO-66(Hf) presented smaller lattice parameter (a = 20.7232 Å), higher crystallite size (0.18 ≤ Φ ≤ 3.33 µm), and smaller SSABET (818 m2·g-1) when compared to its parent UiO-66(Zr) ─ a = 20.7696 Å, 100 ≤ Φ ≤ 250 nm, and SSABET = 1262 m2·g-1. The effect of replacing Zr atoms by Hf in the physical properties of the UiO-66 was deeply evaluated by a spectroscopic study using UV-vis, FTIR, and Raman characterizations. In this case, the Hf presence reduced the band gap of the UiO-66, from 4.07 eV in UiO-66(Zr) to 3.98 eV in UiO-66(Hf). Furthermore, the UiO-66(Hf) showed a blue shift for several FTIR and Raman bands, indicating a stiffening on the implied interatomic bonds when comparing to UiO-66(Zr) spectra. Hafnium was found to clearly favor the capture of iodine [285 g·mol-1, against 230 g·mol-1 for UiO-66(Zr)] and the kinetic evolution of I2 into I3- after 16 h of I2 filtration. Three iodine species were typically identified by Raman spectroscopy and chemometric analysis. These species are as follows: "free" I2 (206 cm-1), "perturbed" I2 (173 cm-1), and I3- (115 and 141 cm-1). It was also verified, by FTIR spectroscopy, that the oxo and hydroxyl groups of the inorganic [M6O4(OH)4] (M = Zr, Hf) cluster were perturbed after the adsorption of I2 into UiO-66(Hf), which was ascribed to the higher acid character of Hf. Finally, with that in mind and considering that the EPR results discard the possibility of a redox phenomenon involving the tetravalent cations (Hf4+ or Zr4+), a mechanism was proposed for the conversion of I2 into I3- in UiO-66─based on an electron donor-acceptor complex between the aromatic ring of the BDC linker and the I2 molecule.

Post-synthetic modification of aluminum trimesate and copper trimesate with TiO2 nanoparticles for photocatalytic applications.

Organic pollutants have been a significant source of concern in recent years due to their facile dissemination and harmful effects. In this work, two different metal-organic frameworks (MOFs) were initially prepared by hydrothermal treatment, namely aluminum trimesate (MIL-100(Al)) and copper trimesate (HKUST-1). These materials were subsequently submitted to a post-synthetic modification step to grow titania nanoparticles on their surface. Anatase nanoparticles with sizes around 5 nm were successfully anchored on MIL-100(Al), and the concentration of TiO2 in this sample was about 68 wt.%. This is the first time that this composite (TiO2@MIL-100(Al)) is reported in the literature. It showed an improved photocatalytic activity, removing 90% of methylene blue (k app = 1.29 h-1), 55% of sodium diclofenac (k app = 0.21 h-1), and 62% of ibuprofen (k app = 0.37 h-1) after four hours of illumination with UV-A light. A significant concentration (14 µM) of reactive oxygen species (ROS) was detected for this composite. HKUST-1 showed a structural collapse during its post-synthetic modification, leading to a non-porous material and providing fewer sites for the heterogeneous nucleation of titania. This behavior led to a low concentration of rutile nanoparticles on HKUST-1 (9 wt.%). However, the obtained composite (TiO2@HKUST) also showed an improved photoactivity compared to HKUST-1, increasing the photodegradation rates evaluated for methylene blue (0.05 h-1 vs. 0.29 h-1), sodium diclofenac (negligible vs. 0.03 h-1), and ibuprofen (0.01 h-1 vs. 0.02 h-1). This work brings new insights concerning the preparation of photocatalysts by growing semiconductor nanoparticles on trimesate-based MOFs.

Effects of spatial constraints and Brønsted acid site locations on para-terphenyl ionization and charge transfer in zeolites.

The locations of Brønsted acid sites (BAS) in the channels of medium-pore zeolites have a significant effect on the spontaneous ionization of para-terphenyl (PP(3)) insofar as spatial constraints determine the stability of transition states and charge-transfer complexes relevant to charge separation. The ionization rates and ionization yield values demonstrate that a strong synergy exists between the H(+) polarization energy and spatial constraints imposed by the channel topology. Spectroscopic and modeling results show that PP(3) incorporation, charge separation, charge transfer and charge recombination differ dramatically among zeolites with respect to channel structure (H-FER, H-MFI, H-MOR) and BAS density in the channel. Compartmentalization of ejected electrons away from the initial site of ionization decreases dramatically the propensity for charge recombination. The main mode of PP(3)(.+) decay is hole transfer to form AlO(4)H(.+) ⋅⋅⋅PP(3) charge-transfer complexes characterized by intense absorption in the visible range. According to the nonadiabatic electron-transfer theory, the small reorganization energy in constrained channels explains the slow hole-transfer rate.

Identification of the EPR signal of S2⁻ in green ultramarine pigments.

Green and blue ultramarine pigments are characterized by the sodalite structure Na(6)(Al(6)Si(6)O(24)) and colored inserted species. These chromophores are sulfur species: S(3)(-) (blue) and S(2)(-) (yellow). Both radicals are encapsulated inside the ß-cages. They contribute to the EPR spectrum of ultramarine pigments. The well-known strong EPR signal observed in all ultramarine pigments Continuous-Wave (CW) spectra has long been assigned to S(3)(-) (g = 2.029). In contrast, the S(2)(-) contribution is still subject to controversy because its signal in ultramarine pigments was not resolved even at low temperature in CW-EPR experiments. In this study, we identify unambiguously for the first time by CW-EPR and field sweep-echo detected (FS-ED) EPR the signal of S(2)(-) in ultramarine pigments and we determine its tensor components: g(1) = 2.69(6), g(2) = 2.03(4) and g(3) = 1.86(4).

Kinetics and characterization of photoinduced long-lived electron-hole pair of p-terphenyl occluded in ZSM-5 zeolites. Effects of aluminium content and extraframework cation.

Diffuse reflectance UV-visible in combination with FT-Raman spectroscopies demonstrate the total incorporation without any solvent of p-terphenyl (p-TP) as an intact molecule in the medium size channel of non-acidic M(n)ZSM-5 (M = Li(+), Na(+), K(+), Rb(+), Cs(+) and n = 0, 3.4, 6.6) zeolites. The combined effects of confinement and electrostatic field induced by alkaline ions in the M(n)ZSM-5 zeolites lead only to weak conformational changes in the occluded p-TP after very long organization periods. The interaction between the counterbalancing cation and p-TP occurs through one phenyl group facially coordinated to the cation near the O atoms binding Al atoms. The laser UV photolysis of p-terphenyl occluded as intact molecules in non-acidic M(n)ZSM-5 zeolites generates long-lived charge separated states. The photoionization induces a p-TP*(+)-electron pair as a primary phenomenon. The recombination of the p-TP*(+)@M(n)ZSM-5*(-) radical cation moiety occurs mainly through unusual electron abstraction from the zeolite framework and p-TP@M(n)ZSM-5*(-)*(+) electron-hole pair formation which exceeds several days at room temperature in Li(6.6)ZSM-5. The very long-lived radical pairs are characterized by conventional DRUVv, FT-Raman and CW-EPR spectroscopy. Two-dimensional hyperfine sublevel correlation (2D-HYSCORE) experiments reveal the structural surroundings of the unpaired electrons through the proper assignment of unpaired electron couplings. The subsequent hole transfer from the radical cation of the channels as well as the final electron-hole pair recombination appear to be largely controlled by the aluminium content, the size of the extra framework cation and the associated local electrostatic field. The effects of the counterbalancing cations have been investigated and because the zeolite electron affinity increases on going from Li(+) to Cs(+), the electron transfer rates increase according to the following order Li(+) < Na(+) < K(+) < Rb(+) < Cs(+).

Long-lived radical cation-electron pairs generated by anthracene sorption in non Brønsted acidic zeolites.

The sorption of anthracene (ANT) in non Brønsted acidic ZSM-5 zeolite through the mere exposure at room temperature of solid ANT and dehydrated zeolite crystals with Li(3.4)(AlO2)n(SiO2)(96-n) chemical formulas per unit cell generates spontaneous ionization of ANT (IP 7.44 eV in the gas phase). In contrast, ANT was found to be sorbed as an intact molecule in M(3.4)ZSM-5 with M = Na+, K+, Rb+, and Cs+. The radical cation (ANT*+) of the long-lived ANT*+@Li(3.4)ZSM-5*- pair was characterized by conventional diffuse reflectance UV-visible and resonance Raman spectrometry. In contrast, the X-band continuous wave (CW) EPR signal was found to be typical of a weakly coupled spin correlated ion pair. The two-dimension hyperfine sublevel correlation (2D-HYSCORE) spectra provide a detailed description of the microenvironment of the trapped electron of the ANT*+@Li(n)ZSM-5*- pair. The trapped electron appears localized in close proximity of occluded ANT*+, Li+, and the Si-O-Al nearest group of the zeolite framework.