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Öğe A highly efficient metal-free electrocatalyst of nitrogen-doped porous carbon nanoflowers toward oxygen electroreduction(Royal Society of Chemistry, 2024) Fan, Xiaoli; Zhang, Yingying; Fan, Longlong; Geng, Qinghong; Zhu, Wei; Doustkhah, Esmail; Li, CuilingMetal-free catalysts offer a desirable alternative to traditional metal-based catalysts. However, it remains challenging to improve the catalytic performance of metal-free catalysts to be as promising as that of metal-based materials. Herein, a polymer-assisted method followed by pyrolysis treatment was employed to synthesize nitrogen (N)-doped porous carbon nanoflowers with nanosheet subunits. Leveraging the unique geometry structure and abundant pyridinic-N active sites, the optimized catalyst exhibits a good half-wave potential of 0.85 V versus reversible hydrogen electrode (vs. RHE) and long-term stability with only 17.0 mV negative shift of the half-wave potential after 10 000 cyclic voltammetry cycles in alkaline electrolyte. This research presents a viable strategy for advancing metal-free catalysts. © The Royal Society of Chemistry 2025.Öğe Exploring coinage bonding interactions in [Au(CN)4]− assemblies with silver and zinc complexes: a structural and theoretical study(Royal society of chemistry, 2025) Giordana, Alessia; Priola, Emanuele; Mahmoudi, Ghodrat; Doustkhah, Esmail; Gomila, Rosa M.; Zangrando, Ennio; Diana, Eliano; Operti, Lorenza; Frontera, AntonioThis study investigates the non-covalent interactions between [Au(CN)4]- anions and silver and zinc complexes, with a particular focus on coinage bonding interactions. Four new complexes, [Ag2(pyNP)2][Au(CN)4]2 (1) [Zn(bipy)3][Au(CN)4]2 (2), [Zn(phen)3][Au(CN)4]2 (3) and [Zn(terpy)(H2O)3][Au(CN)4]2 (4), were synthesized and spectroscopically characterized, including their X-ray solid-state structures, where pyNP is (2-(2-pyridyl)-1,8-naphthyridine, bipy is 2,2 ' bipyridine, phen is 1,10 '-phenantroline and terpy is terpyridine. The [Au(CN)4]- anion exhibits unique anion & ctdot;anion interactions, despite the electrostatic repulsion, forming stable 1D supramolecular polymers in the solid state. Using a combination of X-ray crystallography and DFT calculations, this work characterizes the coordination and non-covalent bonding modes, including Au & ctdot;N coinage bonds. Energy decomposition analysis (EDA), QTAIM, and NCIplot methods were applied to understand the energetics and bonding nature. The study reveals that electrostatic and dispersion forces play critical roles in stabilizing these assemblies, especially in the formation of pi-stacking and T-shaped dimers. These findings offer insights into the design of new materials leveraging coinage bonding in molecular architectures.Öğe Exploring coinage bonding interactions in [Au(CN)4]− assemblies with silver and zinc complexes: a structural and theoretical study(Royal society of chemistry, 2025) Giordana, Alessia; Priola, Emanuele; Mahmoudi, Ghodrat; Doustkhah, Esmail; Gomila, Rosa M.; Zangrando, Ennio; Diana, Eliano; Operti, Lorenza; Frontera, AntonioThis study investigates the non-covalent interactions between [Au(CN)4]− anions and silver and zinc complexes, with a particular focus on coinage bonding interactions. Four new complexes, [Ag2(pyNP)2][Au(CN)4]2 (1) [Zn(bipy)3][Au(CN)4]2 (2), [Zn(phen)3][Au(CN)4]2 (3) and [Zn(terpy)(H2O)3][Au(CN)4]2 (4), were synthesized and spectroscopically characterized, including their X-ray solid-state structures, where pyNP is (2-(2-pyridyl)-1,8-naphthyridine, bipy is 2,2′ bipyridine, phen is 1,10′-phenantroline and terpy is terpyridine. The [Au(CN)4]− anion exhibits unique anion⋯anion interactions, despite the electrostatic repulsion, forming stable 1D supramolecular polymers in the solid state. Using a combination of X-ray crystallography and DFT calculations, this work characterizes the coordination and non-covalent bonding modes, including Au⋯N coinage bonds. Energy decomposition analysis (EDA), QTAIM, and NCIplot methods were applied to understand the energetics and bonding nature. The study reveals that electrostatic and dispersion forces play critical roles in stabilizing these assemblies, especially in the formation of π-stacking and T-shaped dimers. These findings offer insights into the design of new materials leveraging coinage bonding in molecular architectures.Öğe Feeble Single-Atom Pd Catalysts for H2 Production from Formic Acid(Amer Chemical Soc, 2024) Doustkhah, Esmail; Tsunoji, Nao; Mine, Shinya; Toyao, Takashi; Shimizu, Ken-ichi; Morooka, Tetsuro; Masuda, TakuyaSingle-atom catalysts are thought to be the pinnacle of catalysis. However, for many reactions, their suitability has yet to be unequivocally proven. Here, we demonstrate why single Pd atoms (Pd-SA) are not catalytically ideal for generating H-2 from formic acid as a H-2 carrier. We loaded Pd-SA on three silica substrates, mesoporous silicas functionalized with thiol, amine, and dithiocarbamate functional groups. The Pd catalytic activity on amino-functionalized silica (SiO2-NH2/Pd-SA) was far higher than that of the thiol-based catalysts (SiO2-S-Pd-SA and SiO2-NHCS2-Pd-SA), while the single-atom stability of SiO2-NH2/Pd-SA against aggregation after the first catalytic cycle was the weakest. In this case, Pd aggregation boosted the reaction yield. Our experiments and calculations demonstrate that Pd-SA in SiO2-NH2/Pd-SA loosely binds with amine groups. This leads to a limited charge transfer from Pd to the amine groups and causes high aggregability and catalytic activity. According to the density functional calculations, the loose binding between Pd and N causes most of Pd's 4d electrons in amino-functionalized SiO2 to remain close to the Fermi level and labile for catalysis. However, Pd-SA chemically binds to the thiol group, resulting in strong hybridization between Pd and S, pulling Pd's 4d states deeper into the conduction band and away from the Fermi level. Consequently, fewer 4d electrons were available for catalysis.Öğe Metal-support interaction in pt nanodisk-carbon nitride catalyst: insight from theory and experiment(MDPI, 2024) Doustkhah, Esmail; Kotb, Ahmed; Balkan, Timuçin; Assadi, Mohammad Hussein NaseefMetal-support interaction plays a critical role in determining the eventual catalytic activity of metals loaded on supporting substrates. This interaction can sometimes cause a significant drop in the metallic property of the loaded metal and, hence, a drop in catalytic activity in the reactions, especially in those for which low charge carrier transfer resistance is a necessary parameter. Therefore, there should be a case-by-case experimental or theoretical (or both) in-depth investigation to understand the role of support on each metal. Here, onto a layered porous carbon nitride (g-CN), we grew single crystalline Pt nanodisks (Pt@g-CN) with a lateral average size of 21 nm, followed by various characterisations such as electron microscopy techniques, and the measurement of electrocatalytic activity in the O-2 reduction reaction (ORR). We found that intercalating Pt nanodisks in the g-CN interlayers causes an increase in electrocatalytic activity. We investigated the bonding mechanism between carbon support and platinum using density functional theory and applied the d-band theory to understand the catalytic performance. Analysis of Pt's density of states and electronic population across layers sheds light on the catalytic behaviour of Pt nanoparticles, particularly in relation to their thickness and proximity to the g-CN support interface. Our simulation reveals an optimum thickness of similar to 11 angstrom, under which the catalytic performance deteriorates.Öğe Photocatalytic performance of disordered titanium-based hollow nanosheet metal-organic frameworks in wastewater treatment(Elsevier, 2024) Hassandoost, Ramin; Khataee, Alireza; Doustkhah, EsmailBackground: The low long-range order in the crystallinity of metal-organic frameworks (MOFs), commonly known as disordered MOFs, can lead to critical property variations. However, controlling the synthesis conditions for a reproducible outcome is somehow cumbersome, especially if this control is accompanied by morphology engineering to be utilized in photocatalysis where band structure, band gap, surface area, and porosity matter. Methods: Here, we report a crystal and structure-directing approach for the morphology engineering of NTU-9-like MOF aggregated particles (Ti-DHTA(AP)) (composed of Ti4+ and 2,5-dihydroxyterephthalic acid (DHTA)) into a hollow nanosheet (Ti-DHTA(HNS)) morphology. Triethylamine (TEA), here, acts as a structure-directing agent (SDA), and monodispersed polystyrene (PS) as a hard template. The three obtained Ti-DHTAs were eventually investigated in the photocatalytic removal of organic contaminants (dye and pharmaceuticals) and comprehensively characterized by (photo)electrochemical approaches. Significant Findings: The hollow nanosheet-architected Ti-DHTA(HNS) with a superior photocatalytic activity than the other morphologies also exhibits an overall photocatalytic removal (synergic adsorption-photodegradation) of similar to 6.5-fold higher than the commercial TiO2 (P25) under the visible light irradiation, with a degradation turnover (dTON) of 27 mmol h(-1) g(cat)(-1). Ti-DHTA(HNS) also shows promising results in the photocatalytic removal of dye and pharmaceutical wastewater. Photoelectrocatalytic characterizations were provided to compare the photocatalytic performance of synthesized Ti-DHTAs (e.g., in cyclic chronoamperometry (CA), 6-fold higher photoresponse than Ti-DHTA(AP)). Nyquist plots further exhibit that the charge transfer resistance (R-ct) of the unmodified Ti-DHTA(AP) is similar to 10-fold higher than Ti-DHTA(HNS) under visible light illumination. Furthermore, the actual water samples and the reusability of Ti-DHTA(HNS) were investigated. The addition of the radical scavenger agent can confirm the presence of varoius active radicals during the degradation, and hence, the formation of hydroxyl radicals was probed by adding o-phenylenediamine as a trapping agent. During methylene blue (MB) photodegradation, the LC-MS analysis exhibits acetoacetic acid formation (m/z = 102.03) as the dominant intermediate.Öğe Structural and theoretical insights into the influence of thiocyanate ligands on divalent metal complexes with terpyridine derivatives(Elsevier B.V., 2025) Bogdał, Weronika; Jurowska, Anna; Hodorowicz, Maciej; Szklarzewicz, Janusz; Mahmoudi, Ghodrat; Doustkhah, Esmail; Zangrando, Ennio; Frontera, AntonioFour complexes with terpyridine derivative, thiocyanate anion, and selected d-electron metals were studied. The obtained complexes of the formulation [M(ftpy)(SCN)2(CH3OH)]•DMF (M = Mn (1), Co (2), Ni (3)) and [Cu(ftpy)(NCS)2]•H2O (4), where ftpy = 4′‐(furan-2-yl)-2,2′:6′,2′′‐terpyridine, were characterized using FTIR and UV–Vis spectroscopies, magnetic studies, elemental analysis, and single crystal X-ray crystallography. All compounds crystallize in a triclinic crystal system with space group P1¯ and 1–3 are isomorphous and isostructural. The effect of the modification of the terpyridine ligand and the presence of the thiocyanate ligand on the structure has been verified. Interesting dependence was found in the structure of compound 4, where the two thiocyanate ligands are differently coordinated, one via N and the other via S, and the formation of complex dimers connected through hydrogen bonds is observed. The π-stacking interactions and the resulting solid-state architectures of compounds 1–4 were inspected through a combination of DFT calculations, QTAIM, and NCIPlot analyses, and the stability of the complexes was studied by UV–Vis spectroscopy in various solvents. © 2024 The Author(s)Öğe Structural diversity and tetrel bonding significance in lead(ii) complexes with pyrazoylisonicotinoylhydrazone and varied anionic co-ligands(Royal Soc Chemistry, 2024) Mahmoudi, Ghodrat; Garcia-Santos, Isabel; Fernandez-Vazquez, Roi; Gomila, Rosa M.; Castineiras, Alfonso; Doustkhah, Esmail; Zangrando, EnnioFour lead(ii) complexes featuring pyrazoylisonicotinoylhydrazone ligand paired with various anionic co-ligands (azido, thiocyanato, nitrito, and nitrato) were synthesized and thoroughly examined using structural, analytical, and spectroscopic techniques. These ligands, in their mono-deprotonated state, bind to the lead(ii) ion in a tridentate manner through two nitrogen atoms and one oxygen atom. Single-crystal X-ray crystallography revealed the capacity of these molecular complexes to form larger aggregates influenced by the nature of the anion attached to the metal center. In every complex, the lead atom adopts a hemidirectional coordination environment, making it geometrically suited for tetrel bond formation. The crystal structures demonstrate that lead atoms engage in notably short interactions with nitrogen atoms, distances that are shorter than the sum of their van der Waals radii yet exceed the sum of their covalent radii. These tetrel bonds play a pivotal role in weaving the monomeric into self-assembled dimers or extended supramolecular 1D polymers. The formation and characteristics of these intriguing supramolecular structures observed in the solid state of each complex were further explored and validated through density functional theory (DFT) calculations and several computational tools like MEP, NCIPlot, QTAIM, and ELF methods.
