Recent Submissions

  • Synthesis of gold(I)-trifluoromethyl complexes and their role in generating spectroscopic evidence for a gold(I)-difluorocarbene species.

    Nolan, Steven Patrick; Vanden Broeck, Sofie M P; Nelson, David J; Collado, Alba; Falivene, Laura; Cavallo, Luigi; Cordes, David B; Slawin, Alexandra M Z; Van Hecke, Kristof; Nahra, Fady; Cazin, Catherine S J (Chemistry (Weinheim an der Bergstrasse, Germany), Wiley, 2021-04-06) [Article]
    Readily-prepared and bench-stable [Au(CF 3 )(NHC)] compounds were synthesized using new methodologies, starting from [Au(OH)(NHC)], [Au(Cl)(NHC)] or [Au(L)(NHC)]HF 2 precursors (NHC = N-heterocyclic carbene). The mechanism of formation of these species was investigated. Consequently, a new and straightforward strategy for the mild and selective cleavage of a single carbon-fluorine bond from [Au(CF 3 )(NHC)] complexes was attempted and found to be reversible in the presence of an additional nucleophilic fluoride source. This straightforward technique has led to the unprecedented spectroscopic observation of a gold(I)-NHC difluorocarbene species.
  • Lithium-Ion Desolvation Induced by Nitrate Additives Reveals New Insights into High Performance Lithium Batteries

    Wahyudi, Wandi; Ladelta, Viko; Tsetseris, Leonidas; Alsabban, Merfat; Guo, Xianrong; Yengel, Emre; Faber, Hendrik; Adilbekova, Begimai; Seitkhan, Akmaral; Emwas, Abdul-Hamid; Hedhili, Mohamed N.; Li, Lain-Jong; Tung, Vincent; Hadjichristidis, Nikos; Anthopoulos, Thomas D.; Ming, Jun (Advanced Functional Materials, Wiley, 2021-04-02) [Article]
    Electrolyte additives have been widely used to address critical issues in current metal (ion) battery technologies. While their functions as solid electrolyte interface forming agents are reasonably well-understood, their interactions in the liquid electrolyte environment remain rather elusive. This lack of knowledge represents a significant bottleneck that hinders the development of improved electrolyte systems. Here, the key role of additives in promoting cation (e.g., Li+) desolvation is unraveled. In particular, nitrate anions (NO3−) are found to incorporate into the solvation shells, change the local environment of cations (e.g., Li+) as well as their coordination in the electrolytes. The combination of these effects leads to effective Li+ desolvation and enhanced battery performance. Remarkably, the inexpensive NaNO3 can successfully substitute the widely used LiNO3 offering superior long-term stability of Li+ (de-)intercalation at the graphite anode and suppressed polysulfide shuttle effect at the sulfur cathode, while enhancing the performance of lithium–sulfur full batteries (initial capacity of 1153 mAh g−1 at 0.25C) with Coulombic efficiency of ≈100% over 300 cycles. This work provides important new insights into the unexplored effects of additives and paves the way to developing improved electrolytes for electrochemical energy storage applications.
  • Theory-Guided Synthesis of Highly Luminescent Colloidal Cesium Tin Halide Perovskite Nanocrystals

    Liu, Qi; Yin, Jun; Zhang, Bin-Bin; Chen, Jia-Kai; Zhou, Yang; Zhang, Lu-Min; Wang, Lu-Ming; Zhao, Qing; Hou, Jingshan; Shu, Jie; Song, Bo; Shirahata, Naoto; Bakr, Osman; Mohammed, Omar F.; Sun, Hong-Tao (Journal of the American Chemical Society, American Chemical Society (ACS), 2021-04-01) [Article]
    The synthesis of highly luminescent colloidal CsSnX<sub>3</sub> (X = halogen) perovskite nanocrystals (NCs) remains a long-standing challenge due to the lack of a fundamental understanding of how to rationally suppress the formation of structural defects that significantly influence the radiative carrier recombination processes. Here, we develop a theory-guided, general synthetic concept for highly luminescent CsSnX<sub>3</sub> NCs. Guided by density functional theory calculations and molecular dynamics simulations, we predict that, although there is an opposing trend in the chemical potential-dependent formation energies of various defects, highly luminescent CsSnI<sub>3</sub> NCs with narrow emission could be obtained through decreasing the density of tin vacancies. We then develop a colloidal synthesis strategy that allows for rational fine-tuning of the reactant ratio in a wide range but still leads to the formation of CsSnI<sub>3</sub> NCs. By judiciously adopting a tin-rich reaction condition, we obtain narrow-band-emissive CsSnI<sub>3</sub> NCs with a record emission quantum yield of 18.4%, which is over 50 times larger than those previously reported. Systematic surface-state characterizations reveal that these NCs possess a Cs/I-lean surface and are capped with a low density of organic ligands, making them an excellent candidate for optoelectronic devices without any postsynthesis ligand management. We showcase the generalizability of our concept by further demonstrating the synthesis of highly luminescent CsSnI<sub>2.5</sub>Br<sub>0.5</sub> and CsSnI<sub>2.25</sub>Br<sub>0.75</sub> NCs. Our findings not only highlight the value of computation in guiding the synthesis of high-quality colloidal perovskite NCs but also could stimulate intense efforts on tin-based perovskite NCs and accelerate their potential applications in a range of high-performance optoelectronic devices.
  • Optically and Electrocatalytically Decoupled Si Photocathodes with a Porous Carbon Nitride Catalyst for Nitrogen Reduction with Over 61.8% Faradaic Efficiency

    Peramaiah, Karthik; Ramalingam, Vinoth; Fu, Hui-Chun; Alsabban, Merfat; Ahmad, Rafia; Cavallo, Luigi; Tung, Vincent; Huang, Kuo-Wei; He, Jr-Hau (Advanced Materials, Wiley, 2021-03-31) [Article]
    The photoelectrochemical (PEC) approach is attractive as a promising route for the nitrogen reduction reaction (NRR) toward ammonia (NH<sub>3</sub> ) synthesis. However, the challenges in synergistic management of optical, electrical, and catalytic properties have limited the efficiency of PEC NRR devices. Herein, to enhance light-harvesting, carrier separation/transport, and the catalytic reactions, a concept of decoupling light-harvesting and electrocatalysis by employing a cascade n<sup>+</sup> np<sup>+</sup> -Si photocathode is implemented. Such a decoupling design not only abolishes the parasitic light blocking but also concurrently improves the optical and electrical properties of the n<sup>+</sup> np<sup>+</sup> -Si photocathode without compromising the efficiency. Experimental and density functional theory studies reveal that the porous architecture and N-vacancies promote N<sub>2</sub> adsorption of the Au/porous carbon nitride (PCN) catalyst. Impressively, an n<sup>+</sup> np<sup>+</sup> -Si photocathode integrating the Au/PCN catalyst exhibits an outstanding PEC NRR performance with maximum Faradaic efficiency (FE) of 61.8% and NH<sub>3</sub> production yield of 13.8 µg h<sup>-1</sup> cm<sup>-2</sup> at -0.10 V versus reversible hydrogen electrode (RHE), which is the highest FE at low applied potential ever reported for the PEC NRR.
  • Suzuki–Miyaura cross-coupling of esters by selective O–C(O) cleavage mediated by air- and moisture-stable [Pd(NHC)(μ-Cl)Cl]2 precatalysts: catalyst evaluation and mechanism

    Yang, Shiyi; Zhou, Tongliang; Poater, Albert; Cavallo, Luigi; Nolan, Steven P.; Szostak, Michal (Catalysis Science & Technology, Royal Society of Chemistry (RSC), 2021-03-25) [Article]
    The cross-coupling of aryl esters has emerged as a powerful platform for the functionalization of otherwise inert acyl C–O bonds in chemical synthesis and catalysis. Herein, we report a combined experimental and computational study on the acyl Suzuki–Miyaura cross-coupling of aryl esters mediated by well-defined, air- and moisture-stable Pd(II)–NHC precatalysts [Pd(NHC)(μ-Cl)Cl]2. We present a comprehensive evaluation of [Pd(NHC)(μ-Cl)Cl]2 precatalysts and compare them with the present state-of-the-art [(Pd(NHC)allyl] precatalysts bearing allyl-type throw-away ligands. Most importantly, the study reveals [Pd(NHC)(μ-Cl)Cl]2 as the most reactive precatalysts discovered to date in this reactivity manifold. The unique synthetic utility of this unconventional O–C(O) cross-coupling is highlighted in the late-stage functionalization of pharmaceuticals and sequential chemoselective cross-coupling, providing access to valuable ketone products by a catalytic mechanism involving Pd insertion into the aryl ester bond. Furthermore, we present a comprehensive study of the catalytic cycle by DFT methods. Considering the clear advantages of [Pd(NHC)(μ-Cl)Cl]2 precatalysts on several levels, including facile one-pot synthesis, superior atom-economic profile to all other Pd(II)–NHC catalysts, and versatile reactivity, these should be considered as the ‘first-choice’ catalysts for all routine applications in ester O–C(O) bond activation.
  • Engineering Band-Type Alignment in CsPbBr 3 Perovskite-Based Artificial Multiple Quantum Wells

    Lee, Kwangjae; Merdad, Noor A.; Maity, Partha; El-Demellawi, Jehad K.; Lui, Zhixiong; Sinatra, Lutfan; Zhumekenov, Ayan A.; Hedhili, Mohamed N.; Min, Jung-Wook; Min, Jung-Hong; Gutiérrez-Arzaluz, Luis; Anjum, Dalaver H.; Wei, Nini; Ooi, Boon S.; Alshareef, Husam N.; Mohammed, Omar F.; Bakr, Osman (Advanced Materials, Wiley, 2021-03-24) [Article]
    Semiconductor heterostructures of multiple quantum wells (MQWs) have major applications in optoelectronics. However, for halide perovskites—the leading class of emerging semiconductors—building a variety of bandgap alignments (i.e., band-types) in MQWs is not yet realized owing to the limitations of the current set of used barrier materials. Here, artificial perovskite-based MQWs using 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole), tris-(8-hydroxyquinoline)aluminum, and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline as quantum barrier materials are introduced. The structures of three different five-stacked perovskite-based MQWs each exhibiting a different band offset with CsPbBr3 in the conduction and valence bands, resulting in a variety of MQW band alignments, i.e., type-I or type-II structures, are shown. Transient absorption spectroscopy reveals the disparity in charge carrier dynamics between type-I and type-II MQWs. Photodiodes of each type of perovskite artificial MQWs show entirely different carrier behaviors and photoresponse characteristics. Compared with bulk perovskite devices, type-II MQW photodiodes demonstrate a more than tenfold increase in the rectification ratio. The findings open new opportunities for producing halide-perovskite-based quantum devices by bandgap engineering using simple quantum barrier considerations.
  • Chemoselective Hydrogenation of Nitroarenes Using an Air-Stable Base-Metal Catalyst

    Zubar, Viktoriia; Dewanji, Abhishek; Rueping, Magnus (Organic Letters, American Chemical Society (ACS), 2021-03-23) [Article]
    The reduction of nitroarenes to anilines as well as azobenzenes to hydrazobenzenes using a single base-metal catalyst is reported. The hydrogenation reactions are performed with an air-and moisture-stable manganese catalyst and proceed under relatively mild reaction conditions. The transformation tolerates a broad range of functional groups, affording aniline derivatives and hydrazobenzenes in high yields. Mechanistic studies suggest that the reaction proceeds via a bifunctional activation involving metal–ligand cooperative catalysis.
  • [Cu 15 (PPh 3 ) 6 (PET) 13 ] 2+ : a Copper Nanocluster with Crystallization Enhanced Photoluminescence

    Nematulloev, Saidkhodzha; Huang, Renwu; Yin, Jun; Shkurenko, Aleksander; Dong, Chunwei; Ghosh, Atanu; Alamer, Badriah Jaber; Naphade, Rounak; Hedhili, Mohamed N.; Maity, Partha; Eddaoudi, Mohamed; Mohammed, Omar F.; Bakr, Osman (Small, Wiley, 2021-03-19) [Article]
    Due to their atomically precise structure, photoluminescent copper nanoclusters (Cu NCs) have emerged as promising materials in both fundamental studies and technological applications, such as bio-imaging, cell labeling, phototherapy, and photo-activated catalysis. In this work, a facile strategy is reported for the synthesis of a novel Cu NCs coprotected by thiolate and phosphine ligands, formulated as [Cu<sub>15</sub> (PPh<sub>3</sub> )<sub>6</sub> (PET)<sub>13</sub> ]<sup>2+</sup> , which exhibits bright emission in the near-infrared (NIR) region (≈720 nm) and crystallization-induced emission enhancement (CIEE) phenomenon. Single crystal X-ray crystallography shows that the NC possesses an extraordinary distorted trigonal antiprismatic Cu<sub>6</sub> core and a, unique among metal clusters, "tri-blade fan"-like structure. An in-depth structural investigation of the ligand shell combined with density functional theory calculations reveal that the extended CH···π and π-π intermolecular ligand interactions significantly restrict the intramolecular rotations and vibrations and, thus, are a major reason for the CIEE phenomena. This study provides a strategy for the controllable synthesis of structurally defined Cu NCs with NIR luminescence, which enables essential insights into the origins of their optical properties.
  • Construction of hydroxide pn junction for water splitting electrocatalysis

    Zeng, Ye; Cao, Zhen; Liao, Jizhang; Liang, Hanfeng; Wei, Binbin; Xu, Xun; Xu, Haiwang; Zheng, Jiaxian; Zhu, Weijie; Cavallo, Luigi; Wang, Zhoucheng (Applied Catalysis B: Environmental, Elsevier BV, 2021-03-19) [Article]
    NiFe oxyhydroxide (NiFe−OH) has shown promising electrocatalytic oxygen evolution reaction (OER) activity. Here we suggest that the performance of NiFe−OH can be further enhanced by constructing pn junction. Using MnCo carbonate hydroxide (MnCo−CH)@NiFe−OH pn junction as a demonstration, we show that upon the construction of pn junction, the electrons flow from n-type NiFe−OH to MnCo−CH, which consequently generates a positively charged region on NiFe−OH. The density function theory calculation reveals that such an electronic property change results in an improved OER energetics. As a result, the MnCo−CH@NiFe−OH pn junction shows significantly enhanced OER performance that is ∼10 and ∼500 times that of NiFe−OH and MnCo−CH (in terms of the OER currents at the overpotential of 270 mV), respectively. Moreover, the pn junction also shows a greatly boosted hydrogen evolution reaction (HER) and therefore the overall water electrolysis activity that outperforms the Pt/C||RuO2 catalysts.
  • [Ag9(1,2-BDT)6]3–: How Square-Pyramidal Building Blocks Self-Assemble into the Smallest Silver Nanocluster

    Alamer, Badriah Jaber; Bootharaju, Megalamane S.; Kozlov, Sergey M.; Cao, Zhen; Shkurenko, Aleksander; Nematulloev, Saidkhodzha; Maity, Partha; Mohammed, Omar F.; Eddaoudi, Mohamed; Cavallo, Luigi; Basset, Jean-Marie; Bakr, Osman (Inorganic Chemistry, American Chemical Society (ACS), 2021-03-17) [Article]
    The emerging promise of few-atom metal catalysts has driven the need for developing metal nanoclusters (NCs) with ultrasmall core size. However, the preparation of metal NCs with single-digit metallic atoms and atomic precision is a major challenge for materials chemists, particularly for Ag, where the structure of such NCs remains unknown. In this study, we developed a shape-controlled synthesis strategy based on an isomeric dithiol ligand to yield the smallest crystallized Ag NC to date: [Ag<sub>9</sub>(1,2-BDT)<sub>6</sub>]<sup>3-</sup> (1,2-BDT = 1,2-benzenedithiolate). The NC's crystal structure reveals the self-assembly of two Ag square pyramids through preferential pyramidal vertex sharing of a single metallic Ag atom, while all other Ag atoms are incorporated in a motif with thiolate ligands, resulting in an elongated body-centered Ag<sub>9</sub> skeleton. Steric hindrance and arrangement of the dithiolated ligands on the surface favor the formation of an anisotropic shape. Time-dependent density functional theory based calculations reproduce the experimental optical absorption features and identify the molecular orbitals responsible for the electronic transitions. Our findings will open new avenues for the design of novel single-digit metal NCs with directional self-assembled building blocks.
  • A Multivariate Linear Regression Approach to Predict Ethene/1-Olefin Copolymerization Statistics Promoted by Group 4 Catalysts

    Maity, Bholanath; Cao, Zhen; Kumawat, Jugal; Gupta, Virendrakumar; Cavallo, Luigi (ACS Catalysis, American Chemical Society (ACS), 2021-03-17) [Article]
    We report a combined multivariate linear regression (MLR) and density functional theory (DFT) approach for predicting the comonomer incorporation rate in the copolymerization of ethene with 1-olefins. The MLR model was trained to correlate the incorporation rate of a set of 19 experimental group 4 catalysts to steric and electronic features of the dichloride catalyst precursors. Although the assembled experimental data were produced in different laboratories and both propene and 1-hexene copolymerization results were considered, the trained MLR model results in a R2 value of 0.82 and a leave-one-out Q2 value of 0.72. The trained model was validated against a validation set comprising 3 catalysts from the literature and not included in the training set plus one catalyst synthesized by us. Except for one literature catalyst, data in the validation set were predicted with reasonable accuracy. Additionally, a catalyst synthesized by us, for which the MLR model predicted a comonomer incorporation of 4.0%, resulted in a 1-hexene experimental incorporation of 4.5–5%. The trained MLR model was used to predict the comonomer incorporation rate of 10 related zirconocenes having structural features similar to the 19 systems in the training set. We further explored the impact of the precatalyst structure on the comonomer incorporation rate by analyzing a set of 15 zirconocenes having steric and electronic features different from those in the training set. These predictions were validated by DFT calculations.
  • Redox-Neutral Imination of Alcohol with Azide: A Sustainable Alternative to the Staudinger/Aza-Wittig Reaction

    Li, Huaifeng; Lupp, Daniel; Das, Pradip K.; Yang, Li; Goncalves, Theo; Huang, Mei-Hui; El Hajoui, Marwa; Liang, Lan-Chang; Huang, Kuo-Wei (ACS Catalysis, American Chemical Society (ACS), 2021-03-17) [Article]
    The traditional Staudinger/aza-Wittig reaction represents one of the most powerful tools for imine formation. However, for this multistep procedure, the sacrificial phosphine has to be used, resulting in difficulties in the purification process and waste disposal at the same time. Here, we report a redox-neutral azide–alcohol imination methodology enabled by a base-metal nickel PN3 pincer catalyst. The one-step, waste-free, and high atom-economical features highlight its advantages further. Moreover, mechanistic insight suggests a non-metal–ligand cooperation pathway based on the observation of an intermediate and density functional theory calculations.
  • Successes and Challenges of Core/Shell Lead Halide Perovskite Nanocrystals

    Ahmed, Ghada H.; Yin, Jun; Bakr, Osman; Mohammed, Omar F. (ACS Energy Letters, American Chemical Society (ACS), 2021-03-17) [Article]
    Newly emerging perovskite nanocrystals (NCs) have shown a huge potential to be utilized in a gamut of optoelectronic devices due to their superior photoluminescence quantum yield (PLQY), tunable emission wavelength, and facile synthesis protocols at low cost. Despite the enormous progress made in synthetic protocol development, their poor stability against environmental stressors remains a major shortcoming that significantly restricts their practical applications and future commercialization. Of particular interest, core/shell NC engineering has fueled significant progress not only to improve the luminescent properties, reduce exciton recombination, suppress non-radiative recombination, and enhance the charge carrier transport but also, perhaps more importantly, to improve the semiconductor materials’ stability under harsh environmental conditions. Accordingly, this architecture represents a promising avenue to alleviate the stability issue and, therefore, could push the devices’ operational stability and performance forward. In this Focus Review, we explore the successes and challenges of recently reported perovskite core/shell heterostructures and summarize the synthesis methods, the photophysics after shelling, the theoretical approaches, and the applications. Finally, we conclude with a discussion of new opportunities and suggestions to push this research area a step forward.
  • Stable Cr-MFI Catalysts for the Nonoxidative Dehydrogenation of Ethane: Catalytic Performance and Nature of the Active Sites

    De, Sudipta; Ould-Chikh, Samy; Aguilar, Antonio; Hazemann, Jean-Louis; Zitolo, Andrea; Ramirez, Adrian; Telalovic, Selvedin; Gascon, Jorge (ACS Catalysis, American Chemical Society (ACS), 2021-03-16) [Article]
    The nonoxidative catalytic dehydrogenation of ethane allows the production of ethylene at lower temperatures than those applied in steam crackers. This, however, requires stable catalysts that minimize coke production. Here, we report a single-component, promoter-free, low-loading, Cr-based catalyst exhibiting high activity, long-term stability, and improved regeneration properties for the direct dehydrogenation of ethane to ethylene. According to our detailed operando X-ray absorption spectroscopic analysis, the use of all-silica MFI zeolite as support promotes the stabilization of CrII(−O–Si≡)2 species with high coke resistance, even when the dehydrogenation is carried out under high ethane partial pressures (1.5 bar).
  • Hybrid monomer design for unifying conflicting polymerizability, recyclability, and performance properties

    Shi, Changxia; Li, Zi Chen; Caporaso, Lucia; Cavallo, Luigi; Falivene, Laura; Chen, Eugene Y.X. (Chem, Elsevier BV, 2021-03-11) [Article]
    Synthetic polymers have become indispensable for modern life and the global economy. However, the manufacturing and disposal of most of today's polymers follow a linear economy model, which has caused accelerated depletion of finite natural resources, severe worldwide plastics pollution, and enormous materials value loss. The design of future circular polymers considers closed-loop lifecycles toward a circular economy. A key challenge of this promising design includes innovation in monomer structure that could enable not only efficient polymerization to polymers with properties comparable to today's polymers but also selective depolymerization to recover the monomers with high yield and purity. However, these contrasting properties are conflicting in a single monomer structure. This work introduces a hybrid monomer design concept that hybridizes contrasting parent monomer structures to an offspring monomer that can unify conflicting (de)polymerizability and performance properties.
  • CCDC 2061332: Experimental Crystal Structure Determination : 7,14,25,32,43,50-hexaazadecacyclo[50.2.2.22,5.216,19.220,23.234,37.238,41.08,13.026,31.044,49]hexahexaconta-1(54),2,4,6,14,16,18,20,22,24,32,34,36,38,40,42,50,52,55,57,59,61,63,65-tetracosaene ethenylbenzene solvate

    Dey, Avishek; Chand, Santanu; Maity, Bholanath; Bhatt, Prashant; Ghosh, Munmun; Cavallo, Luigi; Eddaoudi, Mohamed; Khashab, Niveen M. (Cambridge Crystallographic Data Centre, 2021-03-11) [Dataset]
  • CCDC 2061332: Experimental Crystal Structure Determination : 7,14,25,32,43,50-hexaazadecacyclo[50.2.2.22,5.216,19.220,23.234,37.238,41.08,13.026,31.044,49]hexahexaconta-1(54),2,4,6,14,16,18,20,22,24,32,34,36,38,40,42,50,52,55,57,59,61,63,65-tetracosaene ethenylbenzene solvate

    Dey, Avishek; Chand, Santanu; Maity, Bholanath; Bhatt, Prashant; Ghosh, Munmun; Cavallo, Luigi; Eddaoudi, Mohamed; Khashab, Niveen M. (Cambridge Crystallographic Data Centre, 2021-03-11) [Dataset]
  • CCDC 2061333: Experimental Crystal Structure Determination : 7,14,25,32,43,50-hexaazadecacyclo[50.2.2.22,5.216,19.220,23.234,37.238,41.08,13.026,31.044,49]hexahexaconta-1(54),2,4,6,14,16,18,20,22,24,32,34,36,38,40,42,50,52,55,57,59,61,63,65-tetracosaene unknown solvate

    Dey, Avishek; Chand, Santanu; Maity, Bholanath; Bhatt, Prashant; Ghosh, Munmun; Cavallo, Luigi; Eddaoudi, Mohamed; Khashab, Niveen M. (Cambridge Crystallographic Data Centre, 2021-03-11) [Dataset]
  • CCDC 2061331: Experimental Crystal Structure Determination : 7,14,25,32,43,50-hexaazadecacyclo[50.2.2.22,5.216,19.220,23.234,37.238,41.08,13.026,31.044,49]hexahexaconta-1(54),2,4,6,14,16,18,20,22,24,32,34,36,38,40,42,50,52,55,57,59,61,63,65-tetracosaene ethylbenzene solvate

    Dey, Avishek; Chand, Santanu; Maity, Bholanath; Bhatt, Prashant; Ghosh, Munmun; Cavallo, Luigi; Eddaoudi, Mohamed; Khashab, Niveen M. (Cambridge Crystallographic Data Centre, 2021-03-11) [Dataset]
  • Twisted Bodipy Derivative: Intersystem Crossing, Electron Spin Polarization and Application As a Novel Photodynamic Therapy Reagent

    Dong, Yu; Kumar, Prashant; Maity, Partha; Kurganskii, Ivan; Li, Shujing; Elmali, Ayhan; Zhao, Jianzhang; Escudero, Daniel; Wu, Huijian; Karatay, Ahmet; Mohammed, Omar F.; Fedin, Matvey V. (Physical Chemistry Chemical Physics, Royal Society of Chemistry (RSC), 2021-03-10) [Article]
    The photophysical properties of a heavy atom-free Bodipy derivative with twisted π-conjugation framework were studied. Efficient intersystem crossing (ISC. Quantum yield: 56%) and exceptionally long-lived triplet state wereobserved (4.5 ms. In solid polymer film matrix; the intrinsic triplet state lifetime in fluid solution is 197.5 μs). Time-resolved electron paramagnetic resonance (TREPR) spectroscopy and DFT computations confirmed the delocalization of triplet state on whole twisted π-conjugation framework, and the zero-field-splitting (ZFS) D parameter is D = −69.5 mT, which is smaller than the 2,6-diiodoBodipy (D = − 104.6 mT). The electron spin polarization (ESP) phase pattern of the triplet state TREPR spectrum of the twisted Bodipy is (a, a, e, a, e, e), which is different from that of 2,6-diiodoBodipy (e, e, e, a, a, a), indicates the electron spin selectivity of the ISC of the twisted structure is different from that of the spin orbital coupling effect. The computed spin-orbit coupling matrix elements (0.154 - 1.964 cm−1), together with the matched energy of the S1/Tn states, the ISC was proposed to be via S1-->T2/T3. The computational results are in agreement with the TREPR results on the electron spin selectivity (the overpopulation of the TY sublevel of the T1 state). The advantage of long-lived triplet state of twisted Bodipy was demonstrated by the efficient singlet oxygen (1O2) photosensitizing (quantum yield = 50.0%) even under severe hypoxia atmosphere (pO2 = 0.2%, v/v). High light toxicity (EC50 = 1.0 μM) and low dark toxicity (EC50 = 78.5 μM) was observed for the twisted Bodipy, cellular studies demonstrate its potential as a novel potent heavy atom-free photodynamic therapy (PDT) reagent.

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