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Samajdar R, Meigooni M, Yang H, Li J, Liu X, Jackson NE, Mosquera MA, Tajkhorshid E, Schroeder CM. Secondary structure determines electron transport in peptides. Proc Natl Acad Sci U S A 2024; 121:e2403324121. [PMID: 39052850 DOI: 10.1073/pnas.2403324121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 06/14/2024] [Indexed: 07/27/2024] Open
Abstract
Proteins play a key role in biological electron transport, but the structure-function relationships governing the electronic properties of peptides are not fully understood. Despite recent progress, understanding the link between peptide conformational flexibility, hierarchical structures, and electron transport pathways has been challenging. Here, we use single-molecule experiments, molecular dynamics (MD) simulations, nonequilibrium Green's function-density functional theory (NEGF-DFT), and unsupervised machine learning to understand the role of secondary structure on electron transport in peptides. Our results reveal a two-state molecular conductance behavior for peptides across several different amino acid sequences. MD simulations and Gaussian mixture modeling are used to show that this two-state molecular conductance behavior arises due to the conformational flexibility of peptide backbones, with a high-conductance state arising due to a more defined secondary structure (beta turn or 310 helices) and a low-conductance state occurring for extended peptide structures. These results highlight the importance of helical conformations on electron transport in peptides. Conformer selection for the peptide structures is rationalized using principal component analysis of intramolecular hydrogen bonding distances along peptide backbones. Molecular conformations from MD simulations are used to model charge transport in NEGF-DFT calculations, and the results are in reasonable qualitative agreement with experiments. Projected density of states calculations and molecular orbital visualizations are further used to understand the role of amino acid side chains on transport. Overall, our results show that secondary structure plays a key role in electron transport in peptides, which provides broad avenues for understanding the electronic properties of proteins.
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Affiliation(s)
- Rajarshi Samajdar
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Moeen Meigooni
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Hao Yang
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Jialing Li
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Xiaolin Liu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Nicholas E Jackson
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Martín A Mosquera
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717
| | - Emad Tajkhorshid
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Charles M Schroeder
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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Renault JP, Huart L, Milosavljević AR, Bozek JD, Palaudoux J, Guigner JM, Marichal L, Leroy J, Wien F, Hervé Du Penhoat MA, Nicolas C. Electronic Structure and Solvation Effects from Core and Valence Photoelectron Spectroscopy of Serum Albumin. Int J Mol Sci 2022; 23:ijms23158227. [PMID: 35897833 PMCID: PMC9331649 DOI: 10.3390/ijms23158227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 12/07/2022] Open
Abstract
X-ray photoelectron spectroscopy of bovine serum albumin (BSA) in a liquid jet is used to investigate the electronic structure of a solvated protein, yielding insight into charge transfer mechanisms in biological systems in their natural environment. No structural damage was observed in BSA following X-ray photoelectron spectroscopy in a liquid jet sample environment. Carbon and nitrogen atoms in different chemical environments were resolved in the X-ray photoelectron spectra of both solid and solvated BSA. The calculations of charge distributions demonstrate the difficulty of assigning chemical contributions in complex systems in an aqueous environment. The high-resolution X-ray core electron spectra recorded are unchanged upon solvation. A comparison of the valence bands of BSA in both phases is also presented. These bands display a higher sensitivity to solvation effects. The ionization energy of the solvated BSA is determined at 5.7 ± 0.3 eV. Experimental results are compared with theoretical calculations to distinguish the contributions of various molecular components to the electronic structure. This comparison points towards the role of water in hole delocalization in proteins.
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Affiliation(s)
- Jean-Philippe Renault
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191 Gif-sur-Yvette, France; (L.H.); (L.M.); (J.L.)
- Correspondence: (J.-P.R.); (C.N.)
| | - Lucie Huart
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191 Gif-sur-Yvette, France; (L.H.); (L.M.); (J.L.)
- Synchrotron SOLEIL, 91192 Saint Aubin, France; (A.R.M.); (J.D.B.); (F.W.)
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, 75252 Paris, France; (J.-M.G.); (M.-A.H.D.P.)
| | | | - John D. Bozek
- Synchrotron SOLEIL, 91192 Saint Aubin, France; (A.R.M.); (J.D.B.); (F.W.)
| | - Jerôme Palaudoux
- Laboratoire de Chimie Physique-Matière et Rayonnement, Sorbonne Université, UMR CNRS 7614, 75252 Paris, France;
| | - Jean-Michel Guigner
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, 75252 Paris, France; (J.-M.G.); (M.-A.H.D.P.)
| | - Laurent Marichal
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191 Gif-sur-Yvette, France; (L.H.); (L.M.); (J.L.)
| | - Jocelyne Leroy
- Université Paris-Saclay, CEA, CNRS, NIMBE, CEA Saclay, 91191 Gif-sur-Yvette, France; (L.H.); (L.M.); (J.L.)
| | - Frank Wien
- Synchrotron SOLEIL, 91192 Saint Aubin, France; (A.R.M.); (J.D.B.); (F.W.)
| | - Marie-Anne Hervé Du Penhoat
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Université, UMR CNRS 7590, MNHN, 75252 Paris, France; (J.-M.G.); (M.-A.H.D.P.)
| | - Christophe Nicolas
- Synchrotron SOLEIL, 91192 Saint Aubin, France; (A.R.M.); (J.D.B.); (F.W.)
- Correspondence: (J.-P.R.); (C.N.)
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Grabarek A, Walczak Ł, Cyganik P. Odd-Even Effect in Peptide SAMs-Competition of Secondary Structure and Molecule-Substrate Interaction. J Phys Chem B 2021; 125:10964-10971. [PMID: 34554757 PMCID: PMC8503877 DOI: 10.1021/acs.jpcb.1c06625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Peptide-based self-assembled
monolayers (SAMs) are well known to
be crucial for biocompatible surface formation on inorganic substrates
applied for implants, biosensors, or tissue engineering. Moreover,
recently these bioinspired nanostructures are also considered
particularly interesting for molecular electronics applications due
to their surprisingly high conductance and thickness-independent capacitance,
which make them a very promising element of organic field-effect transistors
(OFETs). Our structural analysis conducted for a series of prototypic
homooligopeptides based on glycine (Gly) with cysteine (Cys) as a
substrate bonding group chemisorbed on Au and Ag metal substrates
(GlynCys/Au(Ag), n =
1–9) exhibits the formation by these monolayers secondary structure
close to β-sheet conformation with pronounced odd–even structural effect strongly affecting packing density and conformation
of molecules in the monolayer, which depend on the length of molecules
and the type of metal substrate. Our experiments indicate that the
origin of these structural effects is related to the either cooperative
or competitive relationship between the type of secondary structure
formed by these molecules and the directional character of their chemical
bonding to the metal substrate. The current analysis opens up the
opportunity for the rational design of these biologically inspired
nanostructures, which is crucial both for mentioned biological and
electronic applications.
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Affiliation(s)
- Agnieszka Grabarek
- Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Łukasz Walczak
- Science & Research Division, PREVAC sp. z o.o., Raciborska 61, 44-362 Rogow, Poland
| | - Piotr Cyganik
- Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
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Krzykawska A, Wróbel M, Kozieł K, Cyganik P. N-Heterocyclic Carbenes for the Self-Assembly of Thin and Highly Insulating Monolayers with High Quality and Stability. ACS NANO 2020; 14:6043-6057. [PMID: 32343123 DOI: 10.1021/acsnano.0c01733] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
As an organic nanostructure, self-assembled monolayers (SAMs) play a central role in many aspects of nanotechnology, including molecular electronics. In this work, we show that SAMs based on N-heterocyclic carbenes on a Au(111) substrate offer a high level of crystallinity and also exhibit the highest possible packing density. As a result of this structural optimization, defect concentrations were reduced by 2-3 orders of magnitude and thermal stability was ∼100 K higher than those of any other SAMs on Au. The conductivity of these SAMs is ∼4 orders of magnitude lower than that of standard alkanethiols of comparable length, which together with very low defect concentration and high thermal stability makes them a highly interesting material for potential application in organic thin film transistors. The self-assembly of such dense, highly crystalline, and notably stable structures is associated with strong C-Au bonding and the rational design of assembled molecules, resulting in the high mobility of both adsorbate and substrate atoms, as confirmed by the size of the molecular domains and the adsorbate-driven modification of the Au(111) substrate, respectively.
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Affiliation(s)
- Anna Krzykawska
- Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Mateusz Wróbel
- Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
| | - Krzysztof Kozieł
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
| | - Piotr Cyganik
- Smoluchowski Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Krakow, Poland
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Cafferty BJ, Yuan L, Baghbanzadeh M, Rappoport D, Beyzavi MH, Whitesides GM. Charge Transport through Self‐Assembled Monolayers of Monoterpenoids. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Brian J. Cafferty
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
| | - Li Yuan
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
| | - Mostafa Baghbanzadeh
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
| | - Dmitrij Rappoport
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
| | - M. Hassan Beyzavi
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
- Current address: Department of Chemistry and Biochemistry University of Arkansas Fayetteville AR 72701 USA
| | - George M. Whitesides
- Department of Chemistry and Chemical Biology Harvard University 12 Oxford Street Cambridge MA 02138 USA
- Kalvi Institute for Bionano Science and Technology Harvard University 29 Oxford Street Cambridge MA 02138 USA
- Wyss Institute for Biologically Inspired Engineering Harvard University 60 Oxford Street Cambridge MA 02138 USA
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6
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Cafferty BJ, Yuan L, Baghbanzadeh M, Rappoport D, Beyzavi MH, Whitesides GM. Charge Transport through Self-Assembled Monolayers of Monoterpenoids. Angew Chem Int Ed Engl 2019; 58:8097-8102. [PMID: 30989746 DOI: 10.1002/anie.201902997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Indexed: 11/08/2022]
Abstract
The nature of the processes at the origin of life that selected specific classes of molecules for broad incorporation into cells is controversial. Among those classes selected were polyisoprenoids and their derivatives. This paper tests the hypothesis that polyisoprenoids were early contributors to membranes in part because they (or their derivatives) could facilitate charge transport by quantum tunneling. It measures charge transport across self-assembled monolayers (SAMs) of carboxyl-terminated monoterpenoids (O2 C(C9 HX)) and alkanoates (O2 C(C7 HX)) with different degrees of unsaturation, supported on silver (AgTS ) bottom electrodes, with Ga2 O3 /EGaIn top electrodes. Measurements of current density of SAMs of linear length-matched hydrocarbons-both saturated and unsaturated-show that completely unsaturated molecules transport charge faster than those that are completely saturated by approximately a factor of ten. This increase in relative rates of charge transport correlates with the number of carbon-carbon double bonds, but not with the extent of conjugation. These results suggest that polyisoprenoids-even fully unsaturated-are not sufficiently good tunneling conductors for their conductivity to have favored them as building blocks in the prebiotic world.
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Affiliation(s)
- Brian J Cafferty
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - Li Yuan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - Mostafa Baghbanzadeh
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - Dmitrij Rappoport
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA
| | - M Hassan Beyzavi
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA.,Current address: Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR, 72701, USA
| | - George M Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA.,Kalvi Institute for Bionano Science and Technology, Harvard University, 29 Oxford Street, Cambridge, MA, 02138, USA.,Wyss Institute for Biologically Inspired Engineering, Harvard University, 60 Oxford Street, Cambridge, MA, 02138, USA
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7
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Baghbanzadeh M, Pieters PF, Yuan L, Collison D, Whitesides GM. The Rate of Charge Tunneling in EGaIn Junctions Is Not Sensitive to Halogen Substituents at the Self-Assembled Monolayer//Ga 2O 3 Interface. ACS NANO 2018; 12:10221-10230. [PMID: 30226988 DOI: 10.1021/acsnano.8b05217] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This paper describes experiments that are designed to test the influence of terminal groups incorporating carbon-halogen bonds on the current density (by hole tunneling) across self-assembled monolayer (SAM)-based junctions of the form MTS/S(CH2)9NHCOCH nX3- n//Ga2O3/EGaIn (where M = Ag and Au and X = CH3, F, Cl, Br, I). Within the limits of statistical significance, these rates of tunneling are insensitive to the nature of the terminal group at the interface between the SAM and the Ga2O3. The results are relevant to the origin of an apparent inconsistency in the literature concerning the influence of halogen atoms at the SAM//electrode interface on the tunneling current density.
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Affiliation(s)
- Mostafa Baghbanzadeh
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Priscilla F Pieters
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 4 , 9747 AG Groningen , The Netherlands
| | - Li Yuan
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - Darrell Collison
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
| | - George M Whitesides
- Department of Chemistry and Chemical Biology , Harvard University , 12 Oxford Street , Cambridge , Massachusetts 02138 , United States
- Kavli Institute for Bionano Science and Technology , Harvard University 29 Oxford Street , Cambridge , Massachusetts 02138 , United States
- Wyss Institute of Biologically Inspired Engineering , 60 Oxford Street , Cambridge , Massachusetts 02138 , United States
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Bu D, Xiong Y, Tan YN, Meng M, Low PJ, Kuang DB, Liu CY. Understanding the charge transport properties of redox active metal-organic conjugated wires. Chem Sci 2018; 9:3438-3450. [PMID: 29780473 PMCID: PMC5934749 DOI: 10.1039/c7sc04727d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 02/16/2018] [Indexed: 11/28/2022] Open
Abstract
For Rh2-organic molecular wires, we found that weaker coupling systems built using longer bridging ligands exhibit better electrical conductance.
Layer-by-layer assembly of the dirhodium complex [Rh2(O2CCH3)4] (Rh2) with linear N,N′-bidentate ligands pyrazine (LS) or 1,2-bis(4-pyridyl)ethene (LL) on a gold substrate has developed two series of redox active molecular wires, (Rh2LS)n@Au and (Rh2LL)n@Au (n = 1–6). By controlling the number of assembling cycles, the molecular wires in the two series vary systematically in length, as characterized by UV-vis spectroscopy, cyclic voltammetry and atomic force microscopy. The current–voltage characteristics recorded by conductive probe atomic force microscopy indicate a mechanistic transition for charge transport from voltage-driven to electrical field-driven in wires with n = 4, irrespective of the nature and length of the wires. Whilst weak length dependence of electrical resistance is observed for both series, (Rh2LL)n@Au wires exhibit smaller distance attenuation factors (β) in both the tunneling (β = 0.044 Å–1) and hopping (β = 0.003 Å–1) regimes, although in (Rh2LS)n@Au the electronic coupling between the adjacent Rh2 centers is stronger. DFT calculations reveal that these wires have a π-conjugated molecular backbone established through π(Rh2)–π(L) orbital interactions, and (Rh2LL)n@Au has a smaller energy gap between the filled π*(Rh2) and the empty π*(L) orbitals. Thus, for (Rh2LL)n@Au, electron hopping across the bridge is facilitated by the decreased metal to ligand charge transfer gap, while in (Rh2LS)n@Au the hopping pathway is disfavored likely due to the increased Coulomb repulsion. On this basis, we propose that the super-exchange tunneling and the underlying incoherent hopping are the dominant charge transport mechanisms for shorter (n ≤ 4) and longer (n > 4) wires, respectively, and the Rh2L subunits in mixed-valence states alternately arranged along the wire serve as the hopping sites.
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Affiliation(s)
- Donglei Bu
- Department of Chemistry , Jinan University , 601 Huang-Pu Avenue West , Guangzhou 510632 , China .
| | - Yingqi Xiong
- Department of Chemistry , Jinan University , 601 Huang-Pu Avenue West , Guangzhou 510632 , China .
| | - Ying Ning Tan
- Department of Chemistry , Jinan University , 601 Huang-Pu Avenue West , Guangzhou 510632 , China .
| | - Miao Meng
- Department of Chemistry , Jinan University , 601 Huang-Pu Avenue West , Guangzhou 510632 , China .
| | - Paul J Low
- School of Molecular Sciences , University of Western Australia , 35 Stirling Highway , Crawley , 6009 , WA , Australia
| | - Dai-Bin Kuang
- School of Chemistry , SunYat-sen University , Guangzhou 510275 , P. R. China
| | - Chun Y Liu
- Department of Chemistry , Jinan University , 601 Huang-Pu Avenue West , Guangzhou 510632 , China .
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