Subscriber access provided by BRIGHAM YOUNG UNIV
Article
Surface Organization of Polyoxometalate Hybrids Steered by a 2D Supramolecular PTCDI/Melamine Network Andrés Lombana, Corentin Rinfray, Florence Volatron, Guillaume Izzet, Nicolas Battaglini, Sandra Alves, Philippe Decorse, Philippe Lang, and Anna Proust J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.5b11945 • Publication Date (Web): 19 Jan 2016 Downloaded from http://pubs.acs.org on January 26, 2016
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
The Journal of Physical Chemistry C is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
Surface Organization of Polyoxometalate Hybrids Steered by a 2D Supramolecular PTCDI/Melamine Network Andrés Lombana, †, ‡ Corentin Rinfray, §,‡ Florence Volatron, § Guillaume Izzet, § Nicolas Battaglini,† Sandra Alves, § Philippe Decorse, † Philippe Lang,*, † and Anna Proust*,§ §Sorbonne Universités, UPMC Univ Paris 06, CNRS UMR 8232, Institut Parisien de Chimie Moléculaire, Université Pierre et Marie Curie, 4 place Jussieu, F-75005 Paris, France. † Sorbonne Paris Cité, Université Paris Diderot, CNRS UMR 7086, ITODYS, Univ Paris 07, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France. ‡These authors contributed equally
ABSTRACT
A 2D supramolecular honeycomb network built on hydrogen bonding of Perylene-3,4,9,10tetracarboxylic acid diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (Melamine) has been selfassembled on Au(111) by a solution processed method. The ability of the porous network to host functional molecular oxides or polyoxometalates (POMs) has been investigated using a functionalized species
[PW11O39Ge{p-C6H4-C≡C-C6H4-NHC(O)(CH2)4{-CH(CH2)2S-S-}}]4-
(KWGe[S-S]):
this
ACS Paragon Plus Environment
1
The Journal of Physical Chemistry
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 2 of 25
inorganic/organic hybrid built on a Keggin-type POM core and an organic tether incorporating a thioctic acid function has been designed to enhance the host-guest interaction by the formation of covalent Au-S bonds. XPS analysis confirmed the presence of the POMs that are covalently held onto the surface. Probed by STM operating under ambient conditions, the spatial organization of the POMs display some reminiscence of the organic template, while monitoring the POM deposition at various immersion times by PM-IRRAS showed that the POM raising at the substrate is fostered.
Keywords: 2D supramolecular network, H-bonding, polyoxometalates, environmental STM, PMIRRAS, organic-inorganic hybrids, molecular oxides
INTRODUCTION The development of 2D materials following a bottom-up approach is strongly related to potential applications in emergent molecular nanosciences.1 While the field has long been dominated by selfassembled monolayers of thiolates on metals and especially gold,2 surface-based supramolecular chemistry is rapidly growing. The first studies involved molecules that were sublimated and Ultra High Vacuum techniques of imaging,3 4 which can limit the subsequent use of the resulting networks. Selfassemblies are now commonly performed by solution processed methods and are driven by various molecular interaction types, including hydrogen bonding,5
6 7
alkyl chain interdigitation8
9
or metal-
ligand coordination.10 11 12 Of special interest is the elaboration of open networks that can act as templates to steer the organization of functional guest molecules. Beyond surface patterning at the nanometer scale, this approach also enables the direct addressing and manipulation of single molecules with a STM tip.13
14
Several types of molecules have thus been immobilized on nanoporous networks, including thiols and
ACS Paragon Plus Environment
2
Page 3 of 25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
C60
3
but examples of metallic complexes are still limited,15 although they could bring additional
functionalities due to their redox, magnetic or optical properties. Electro-spray deposition of the wellknown [Mn12O12(CH3CO2)16(H2O)4] single molecule magnet onto a hydrogen-bonded array of perylene3,4,9,10-tetracarboxylic acid diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (Melamine) was not as efficient as expected, probably because of size mismatching and/or lack of suitable interactions between the host and the guests.16 Among molecules that could power the development of molecular nanosciences, polyoxometalates (POMs) are attracting much attention: these nano-scaled molecular oxides indeed display an unmatched variety of molecular structures and electronic properties
17
that could find
applications in molecular electronics, spintronics or even quantum computing.18 19 A significant step has been very recently achieved with the design of POM-based memory cells compatible with CMOS (Complementary Metal Oxide semiconductor) technology.19 Since POMs cannot be sublimated, their processing is a crucial issue that has been approached using either electrostatic or covalent interactions.20 We have recently described the covalent anchorage of POM-based hybrids on carbon, gold and silicon substrates, for surface nano-patterning or studies of electron transfer kinetics from the substrate to the POM layers.21 22 23 24 25 However at low surface density, we observed that the POMs first form islets on surface, probably owing to their propensity to aggregate, which render difficult their structuration on a large scale. To address their physical properties at the solid device level, a higher degree of the POM layer organization and a better control of the POM dispersion are needed. This prompted us to investigate the deposition of POMs on a preformed 2D supramolecular PTCDI/Melamine honeycomb network assembled at a liquid-gold interface. To enhance the interactions between the naked gold nanopores and the POMs through the formation of covalent Au-S bonds, an inorganic/organic hybrid built on a Keggin-type polyoxometalate core and an organic tether
ACS Paragon Plus Environment
3
The Journal of Physical Chemistry
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Page 4 of 25
incorporating a thioctic acid function has been designed and assembled following C-C and peptide-bond couplings.26
27 28
In this contribution we will thus describe the molecular synthesis and characterization
of [PW11O39Ge{p-C6H4-C≡C-C6H4-NHC(O)(CH2)4{-CH(CH2)2S-S-}}]4- as a tetrabutylammonium salt and the formation of the PTCDI/Melamine honeycomb networks for the hosting of the POMs as followed by STM imaging under environmental conditions. The effect of the organic template on the organization and orientation of the POMs have then been inferred by STM and PM-IRRAS, respectively.
EXPERIMENTAL SECTION General Triethylamine and acetonitrile were distilled from CaH2. All other reagents were used as supplied, in particular 1,3,5-triazine-2,4,6-triamine (Melamine) from Fluka (HPLC, purity ≥99.0%), (3,4,9,10-Perylenetetracarboxylic
diimide)
PTCDI
from
Alfa
Aesar
(purity
>98
%)
and
Dimethylformamide (DMF) from Sigma-Aldrich (CHROMASOLV® Plus for HPLC, purity ≥99.9%). Gold on mica surfaces (Au (111), 200 nm thick gold film evaporated on mica) were purchased from Phasis, Geneva. PM-IRRAS measurements were performed using a Nicolet 8700 spectrometer (sum of 2000 scans, 4 cm−1 resolution, 0.47 cm−1 optical velocity) along with a photoelastic modulator PEM-90 (Hind Instruments). STM studies were performed using a Molecular Imaging PicoScan® microscope operating under ambient conditions in the constant current mode. Typical voltage and current ranges were 200 mV - 1000 mV and 1pA - 200pA, respectively. The software WSxM was used for image processing.29 The X-ray photoelectron spectra were recorded using a THERMO VG ESCALAB 250 spectrometer equipped with a micro-focused, monochromatic Al Kα X-ray beam (1486.6 eV) and a magnetic lens. A 500 μm X-ray spot size was used at a power of 150 Watt, 15 KV. The samples were
ACS Paragon Plus Environment
4
Page 5 of 25
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
The Journal of Physical Chemistry
pressed against conductive double-sided adhesive tapes on sample holders and pumped overnight in the fast entry lock (P
