Correction: Tuning the optical properties of the metal-organic framework UiO-66 via ligand functionalization.

Correction for 'Tuning the optical properties of the metal-organic framework UiO-66 via ligand functionalization' by Marvin Treger et al., Phys. Chem. Chem. Phys., 2023, 25, 6333-6341, https://doi.org/10.1039/D2CP03746G.

Fragment-based approach for the efficient calculation of the refractive index of metal-organic frameworks.

Increasing demands on materials in the field of optical applications require novel materials. Metal-organic frameworks (MOFs) are a prominent class of hybrid inorganic-organic materials with a modular layout. This allows the fine-tuning of their optical properties and the tailored design of optical systems. In the present theoretical study, an efficient method to calculate the refractive index (RI) of MOFs is introduced. For this purpose, the MOF is split into disjoint fragments, the linkers and the inorganic building units. The latter are disassembled until metal ions are obtained. The static polarizabilities are calculated individually using molecular density functional theory (DFT). From these, the MOF's RI is calculated. To obtain suitable polarizabilities, an exchange-correlation functional benchmark was performed first. Subsequently, this fragment-based approach was applied to a set of 24 MOFs including Zr-based MOFs and ZIFs. The calculated RI values were compared to the experimental values and validated using HSE06 hybrid functional DFT calculations with periodic boundary conditions. The examination of the MOF set revealed a speed up of the RI calculations by the fragment-based approach of up to 600 times with an estimated maximal deviation from the periodic DFT results below 4%.

Development of high refractive index UiO-66 framework derivatives via ligand halogenation.

UiO-66 is a Zr-based metal-organic framework (MOF) with exceptional chemical and thermal stability. The modular design of a MOF allows the tuning of its electronic and optical properties to obtain tailored materials for optical applications. Making use of the halogenation of the 1,4-benzenedicarboxylate (bdc) linker, the well-known monohalogenated UiO-66 derivatives were examined. In addition, a novel diiodo bdc based UiO-66 analogue is introduced. The novel UiO-66-I2 MOF is fully characterized experimentally. By applying density functional theory (DFT), fully relaxed periodic structures of the halogenated UiO-66 derivatives are generated. Subsequently, the HSE06 hybrid DFT functional is used to calculate the electronic structures and optical properties. The obtained band gap energies are validated with UV-Vis measurements to assure a precise description of the optical properties. Finally, the calculated refractive index dispersion curves are evaluated underlining the capabilities to tailor the optical properties of MOFs by linker functionalization.

Tuning the optical properties of the metal-organic framework UiO-66 via ligand functionalization.

Metal-organic frameworks (MOFs) are a promising class of materials for optical applications, especially due to their modular design which allows fine-tuning of the relevant properties. The present theoretical study examines the Zr-based UiO-66-MOF and derivatives of it with respect to their optical properties. Starting from the well-known monofunctional amino- and nitro-functionalized UiO-66 derivatives, we introduce novel UiO-66-type MOFs containing bifunctional push-pull 1,4-benzenedicarboxylate (bdc) linkers. The successful synthesis of such a novel UiO-66 derivative is also reported. It was carried out using a para-nitroaniline (PNA)-based bdc-analogue linker. Applying density functional theory (DFT), suitable models for all UiO-66-MOF analogues were generated by assessing different exchange-correlation functionals. Afterwards, HSE06 hybrid functional calculations were performed to obtain the electronic structures and optical properties. The detailed HSE06 electronic structure calculations were validated with UV-Vis measurements to ensure reliable results. Finally, the refractive index dispersion of the seven UiO-66-type materials is compared, showing the possibility to tailor the optical properties by the use of functionalized linker molecules. Specifically, the refractive index can be varied over a wide range from 1.37 to 1.78.

Inside/Outside: Post-Synthetic Modification of the Zr-Benzophenonedicarboxylate Metal-Organic Framework.

The Zr-based metal-organic framework, Zr-bzpdc-MOF, contains the photoreactive linker molecule benzophenone-4,4'-dicarboxylate (bzpdc) which imparts the possibility for photochemical post-synthetic modification. Upon irradiation with UV light, the keto group of the benzophenone moiety will react with nearly every C-H bond-containing molecule. Within this paper, we further explore the photochemical reactivity of the Zr-bzpdc-MOF, especially with regard to which restrictions govern internal versus external reactions. We show that apart from reactions with C-H bond-containing molecules, the MOF reacts also with water. By studying the reactivity versus linear alcohols we find a clear delineation in that shorter alcohol molecules (up to butanol as a borderline case) react with photoexcited keto groups throughout the whole crystals whereas longer ones react only with surface-standing keto groups. In addition, we show that with the alkanes n-butane to n-octane, the reaction is restricted to the outer surface. We hypothesize that the reactivity of the Zr-bzpdc-MOF versus different reagents depends on the accessibility of the pore system which in turn depends mainly on the size of the reagents and on their polarity. The possibility to direct the post-synthetic modification of the Zr-bzpdc-MOF (selective modification of the whole pore system versus surface modification) gives additional degrees of freedom in the design of this metal-organic framework for shaping and for applications.

Expanding the Group of Porous Interpenetrated Zr-Organic Frameworks (PIZOFs) with Linkers of Different Lengths.

A Zr-based MOF of the PIZOF type, which consists of two independent and mutually interpenetrating UiO-type frameworks with [Zr6O4(OH)4(O2C)12] nodes, does not only form with a PEPEP dicarboxylic acid (P = phenylene, E = ethynylene). Also dicarboxylic acids with the shorter PPPP and PEPP spacers were found to give PIZOFs, denoted PPPP-PIZOF and PEPP-PIZOF, respectively. Reducing the spacer length even further to a PEEP segment caused a switchover to the formation of a UiO framework. The hysteresis in the Ar sorption curve of PEPP-PIZOF-1 and the slightly too large amount of combustion residue from PPPP-PIZOF-1 suggest structural defects. These hint at a mismatch between the requirement of the optimal linker length for PIZOF formation and the lengths of the PEPP and PPPP dicarboxylates. Nevertheless, these dicarboxylates prefer the formation of a PIZOF over the formation of a UiO structure. PEPEP-PIZOF-2, PPPP-PIZOF-1, and PEPP-PIZOF-1 are stable in air up to 325, 350, and 300 °C, respectively, and have BET surface areas of 2350, 2020, and 1650 m2 g-1, respectively. PEPEP-PIZOFs, even those with very hydrophilic oligo(ethylene glycol) side chains on the linkers, are very stable in water and also during drying from a water-wetted state. On the contrary, PEPP-PIZOF-1 and PPPP-PIZOF-1 that had been exposed to water required exchange of water for ethanol before drying to mostly preserve the framework. The results emphasize the importance of differentiating between framework damage caused through hydrolysis in water and through drying from a water-wetted state. The sensitivity of PEPP-PIZOF-1 and PPPP-PIZOF-1 against drying from a water-wetted state may be the consequence of defects. The drying stability of water-wetted PEPEP-PIZOFs lets us suggest that reversible bending of the linkers contributes to the stability of the PEPEP-PIZOFs.

Impact of prior interventions on outcomes during per oral endoscopic myotomy.

BACKGROUND: Per oral endoscopic myotomy (POEM) is performed by accessing the submucosal space of the esophagus. This space may be impacted by prior interventions such as submucosal injections, dilations or previous myotomies. These interventions could make POEM more difficult and may deter surgeons during their initial experience. We sought to determine the impact of prior interventions on our early experience. METHODS: Prospective, single-center study of consecutive patients undergoing POEM. Patients were grouped according to their anticipated complexity: Group A: no prior interventions (N = 19); Group B: prior interventions such as submucosal injections and/or dilations (N = 11) and  Group C: sigmoidal esophagus, prior esophageal surgery, balloon dilation >30 mm (N = 8). We compared operative times, inadvertent mucosotomy rates, complications and short-term outcomes between groups. RESULTS: A total of 38 patients underwent POEM for achalasia subtypes: I (N = 9), II (N = 19) and III (N = 7). Three had other dysmotility disorders. Patients between the groups were similar. Operative times were similar between Group A and Group B but significantly longer for Group C (133 vs. 132 vs. 210 min, p = 0.001). Mucosotomy rates were highest in Group A (6/19) with 1 each in Group B/C (p = 0.46). One patient in Group A required an esophageal stent. Eckardt scores improved in all groups (6-1; 8-2; 6-0.5, p = 0.73), and postoperative GERD-HRQL scores were similar. One patient underwent laparoscopic myotomy for persistent symptoms with no improvement, and one patient underwent esophagectomy for a sigmoid esophagus and persistent symptoms despite adequate myotomy. CONCLUSION: A prior intervention does not seem to impact short-term clinical outcomes with POEM. Patients who had submucosal injections or small caliber dilations are similar to patients with no prior inventions; however, patients with a sigmoid-shaped esophagus and/or a prior myotomy require nearly double the operative time. Endoscopists undertaking POEM should consider these during their learning curve.

Tri-comparison of Laparoscopic Nissen, Hill, and Nissen-Hill Hybrid Repairs for Uncomplicated Gastroesophageal Reflux Disease.

BACKGROUND: A randomized controlled trial (RCT) showed that laparoscopic Nissen fundoplication (LNF) and Hill (LHR) repairs are equivalent in treating uncomplicated GERD. We combined both repairs to create a laparoscopic Nissen-Hill Hybrid repair (HYB). The purpose of this study is to compare clinical and objective outcomes of a matched group of HYB to the two cohorts of the RCT. METHODS: A retrospective analysis of prospectively collected data from the RCT and a prospectively collected data base was performed. Data were collected preoperatively, postoperatively short-term (ST) at 6 weeks and mid-term (MT) at 6-12 months. Evaluation was standardized according to the RCT and included three quality of life metrics (QOLRAD, GERD-HRQL, Dysphagia), endoscopy, manometry, pH testing, and barium swallow. RESULTS: There were 51 HYB, 46 LNF, and 56 LHR patients. Age, BMI, follow-up, and gender were comparable. QOLRAD, HRQL, PPI use, DeMeester scores, and pH% time <4 significantly improved in all groups and were equivalent. Anatomic recurrence was seen in five LNF, four LHR, and two HYB patients. Reoperations were performed in three LHR, two LNF, and zero HYB patients. CONCLUSION: Tri-comparison shows that HYB is a promising alternative to LHR and LNF. Side effects were not increased and there were fewer reoperations for failure.

A Matched Comparison of Per Oral Endoscopic Myotomy to Laparoscopic Heller Myotomy in the Treatment of Achalasia.

BACKGROUND: Per oral endoscopic myotomy (POEM) is increasingly utilized to treat patients with achalasia. Early results have demonstrated significant improvement of symptoms, but there are concerns about postoperative reflux. With only limited comparative data available, we sought to compare POEM to laparoscopic Heller myotomy (LHM) with partial fundoplication. METHODS: This is a retrospective review of 42 POEM and 84 LHM patients undergoing primary myotomy for achalasia. Patients were matched by achalasia type, by Eckardt and dysphagia scores, and by quality of life (QOL) metrics. Analysis at 6-12-month follow-up evaluated these metrics, PPI use, pH, manometric, and endoscopic data. RESULTS: We matched 25 patients with achalasia types I (6), II (13), and III (6). Follow-up was longer for LHM at 158.1 (36.5-272.9) weeks versus 36.2 (22.2-41.2) weeks (p = 0.001). Eckardt scores, QOL metrics, and dysphagia significantly improved in both groups. DeMeester scores and total percent time less than 4 were abnormal in both groups and comparable (p = 0.925 and p = 0.838). Esophagitis was seen in 53.4 % (POEM) and 31.6 % (LHM) (Yates' p = 0.91), and PPI use was equivalent at 36 %. CONCLUSION: Early clinical outcomes are excellent with POEM and comparable to the standard of care LHM. Long-term follow-up is required as concerns for reflux persist.

Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition.

In this study we present a three-step process for the low-temperature chemical bath deposition of crystalline ZnO films on glass substrates. The process consists of a seeding step followed by two chemical bath deposition steps. In the second step (the first of the two bath deposition steps), a natural polysaccharide, namely hyaluronic acid, is used to manipulate the morphology of the films. Previous experiments revealed a strong influence of this polysaccharide on the formation of zinc oxide crystallites. The present work aims to transfer this gained knowledge to the formation of zinc oxide films. The influence of hyaluronic acid and the time of its addition on the morphology of the resulting ZnO film were investigated. By meticulous adjustment of the parameters in this step, the film morphology can be tailored to provide an optimal growth platform for the third step (a subsequent chemical bath deposition step). In this step, the film is covered by a dense layer of ZnO. This optimized procedure leads to ZnO films with a very high electrical conductivity, opening up interesting possibilities for applications of such films. The films were characterized by means of electron microscopy, X-ray diffraction and measurements of the electrical conductivity.

Selective adsorption of polychlorinated dibenzo-p-dioxins and dibenzofurans by the zeosils UTD-1, SSZ-24, and ITQ-4.

Zeosils are microporous solids with a pure silica framework. Due to their hydrophobic properties, zeosils are ideal host materials for the adsorption of hydrophobic guest molecules. We tested zeosils with different pore diameters (UTD-1, SSZ-24 and ITQ-4 as well as CIT-5) for the selective adsorption of the polychlorinated dibenzo-p-dioxins and dibenzofurans. This group of highly toxic substances contains 210 congeners that possess similar chemical properties, but differ in their size and shape. In the experiment, polychlorinated dibenzo-p-dioxins and dibenzofurans were extracted from fly ash of a waste incinerator, adsorbed on amorphous silica, then thermally desorbed and flushed over a sequential arrangement of the zeosils at elevated temperature by a stream of nitrogen. ITQ-4 with the smallest pore diameter was placed first, followed by SSZ-24 and, finally, by UTD-1 with the largest pore diameter. After the experiment, the zeosils were analysed for their contents of the different congeners. The results show that the sorption of the congeners occurs selectively and that it is governed by the size and the shape of the dioxin molecules, which in turn depend on the number of chlorine atoms and the pattern of chlorine substitution (regioisomers). Geometrical reasoning as well as molecular dynamics calculations on the zeosil structures and on the dioxin molecules were helpful in rationalising the results. This work represents an especially complex case of the molecular sieving effect and may lead to a selective on-line monitoring of the concentrations of dioxin molecules in waste gases of industrial combustion processes. The size- and shape-selective sorption of dioxin molecules may also bear some resemblance to the molecular recognition process that occurs in nature at the aryl hydrocarbon receptor.