New Journal of Chemistry c4nj00617h
Synthesisof glycoluril-tetrathiafulvalene molecular Q1 clips for electron-deficient neutral guests through Q2
a straightforward Diels–Alder strategy Marie Hardouin-Lerouge, Yoann Cotelle, Ste´phanie Legoupy and Pie´trick Hudhomme*
An electroactive glycoluril-based molecular clip incorporating tetrathiafulvalene (TTF) sidewalls was synthesized and was shown to complex the electron-poor guest F4-TCNQ in a 1 : 1 stoichiometry.
Please check this proof carefully.Our staff will not read it in detail after you have returned it.
Translation errors between word-processor files and typesetting systems can occur so the whole proof needs to be read.
Please pay particular attention to: tabulated material; equations; numerical data; figures and graphics; and references. If you have not already indicated the corresponding author(s) please mark their name(s) with an asterisk. Please e-mail a list of corrections or the PDF with electronic notes attached – do not change the text within the PDF file or send a revised manuscript. Corrections at this stage should be minor and not involve extensive changes. All corrections must be sent at the same time.
Please bear in mind that minor layout improvements, e.g. in line breaking, table widths and graphic placement, are routinely applied to the final version.
Please note that, in the typefaces we use, an italic vee looks like this:n, and a Greek nu looks like this:n.
We will publish articles on the web as soon as possible after receiving your corrections;no late corrections will be made.
Please return yourfinalcorrections, where possible within48 hoursof receipt, by e-mail to: njc@rsc.org
Queries for the attention of the authors
Journal: NJC Paper: c4nj00617h
Title: Synthesis of glycoluril-tetrathiafulvalene molecular clips for electron-deficient neutral guests through a straightforward Diels–Alder strategy
Editor’s queries are marked on your proof like thisQ1,Q2, etc. and for your convenience line numbers are indicated like this5,10,15, ...
Please ensure that all queries are answered when returning your proof corrections so that publication of your article is not delayed.
Query
reference Query Remarks
Q1 For your information: You can cite this article before you receive notification of the page numbers by using the following format: (authors), New J. Chem., (year), DOI:
10.1039/c4nj00617h.
Q2 Please carefully check the spelling of all author names.
This is important for the correct indexing and future citation of your article. No late corrections can be made.
Q3 Two different terms have been used to describe ‘‘F4- TCNQ’’ (tetracyanoquinodimethane derivative and tetrafluoro-tetracyanoquinodimethane). Please check this carefully and indicate any changes required here.
Q4 Ref. 8: Please provide the page (or article) number(s).
Q5 Ref. 11: Can this reference be updated?
Synthesis of glycoluril-tetrathiafulvalene
Q1 Q2molecular clips for electron-deficient neutral
guests through a straightforward Diels–Alder strategy†
Marie Hardouin-Lerouge, Yoann Cotelle, Ste´phanie Legoupy and Pie´trick Hudhomme*
An electroactive molecular clip incorporating tetrathiafulvalene (TTF) sidewalls grafted on a glycoluril platform has been synthesized using a straightforward Diels–Alder strategy. This way of attachment to the glycoluril U-shape scaffold afforded a rigidified and closed receptor for which the electron-rich TTF pincers are expected to be at a suitable distance for sandwiching neutral guests through donor–acceptor interactions. The efficient complexation ability of this host architecture toward one molecule of tetracyanoquinodimethane derivative (F4- TCNQ) in solutionhas been demonstrated using cyclic voltammetry and UV-Visible titration methods. Q3
Introduction
Since the last two decades, the rapid expansion in supramolecular chemistry has resulted in the synthesis of molecular receptors prone to act as efficient host–guest systems with the capability of recognizing specific chemical species through weak non-covalent interactions.1 Considerable efforts are currently devoted to the extension of supramolecular principles for catalysis, biological and biomedicinal applications2and for the development of molecular devices and machines.3While the selective recognition of cations and anions have attracted considerable research interest in terms of applications in various areas of supramolecular chemistry, the development of molecular sensors devoted to neutral molecules using host–guest interactions remains a real challenge. In this area of interest, the concept of molecular clips and tweezers opens a fascinating field of research for this molecular recognition of neutral guests exploring the potentialities of donor–acceptor inter- actions.4Since the pioneering work of Chen and Whitlock using caffeine units linked to a flexible linker,5 intensive research was initially developed by Zimmerman,6 Kla¨rner7 and their collaborators focusing on the use of a rigidified spacer for orienting acridine or polyarene as weakp-donating interaction sites. Among strategies available for enhancing the guest recognition process, the incorporation of redox-active units into host molecules should increase intermolecular donor–
acceptor interactions. In this context, the use of tetrathiafulvalene (TTF) appears particularly attractive thanks to itsp-electron donor ability resulting in the formation of famous donor–acceptor complexes.8 More recently, this electron donor framework has proven to be an efficient electroactive brick in various topics of supramolecular chemistry ranging from electrochemical sensing to switchable architectures, in particular thanks to its peculiar electronic characteristics with its two successive reversible oxida- tion steps giving rise to three stable redox states.9 Despite the broad development of TTF chemistry,10only a few number of TTF- based molecular clips built around a more or less rigidified scaffold have been synthesized and employed for sensing neutral guests. For example, the calix-[4]pyrrole platform decorated with four appended TTF units was shown to act in its 1,3-alternate conformation as a sandwich-like host molecule for different electron-deficient guests with the ability of releasing the guest by addition of chloride anions.11 A calix[2]pyrrole[2]thiophene based architecture incorporating two TTF units was described and its ability to function as a receptor for TCNQ was achieved.12 Preorganized calix[4]arene-pyrrolotetrathiafulvalene derivatives were also recently investigated as efficient receptors for sensing electron-deficient neutral molecules with the formation of charge- transfer complexes in solution.13Molecular clips containing two TTF moieties connected to the opposite sides of a 1,2,4,5-substituted benzene backbone through eight-membered dithia rings were described as relatively rigid sensors able to adopt a special cis-conformation for recognition of neutral guests.14
The glycoluril-based scaffold historically developed by Nolte and colleagues has become a very popular building block for the preparation of rigidified molecular clips for binding aromatic guests inside the cavity thanks to a suitable preorganization of the 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55
Cite this:DOI: 10.1039/c4nj00617h
Universite´ d’Angers, Laboratoire MOLTECH-Anjou, CNRS UMR 6200, 2 Bd Lavoisier, 49045 Angers, France. E-mail: pietrick.hudhomme@univ-angers.fr
†Electronic supplementary information (ESI) available: Experimental proce- dures, characterization data, electrochemical and UV-Visible titration results.
See DOI: 10.1039/c4nj00617h Received (in Montpellier, France) 18th April 2014,
Accepted 26th August 2014 DOI: 10.1039/c4nj00617h
www.rsc.org/njc
This journal isc The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014 New J. Chem.,2014,00, 1 8 |1
NJC
PAPER
aromatic binding sites.15To our knowledge, only receptor2built around the glycoluril platform and incorporating TTF sidewalls has been described before we started to investigate this topic. Molecular clip2was synthesized by an acid-catalyzed condensation followed by a cross-coupling to link the glycoluril scaffold to the TTF arms.
This host2was shown to complex an electron-deficient bipyridinium guest such as a paraquat type molecule (Scheme 1).16
Using an alternative synthetic strategy involving a [4+2]
cycloaddition reaction, we describe in this paper the straight- forward synthesis of new glycoluril-based molecular clip1. Such a strategy allows integration of TTF derivatives presenting a larger p-extension as sidewalls, in order to increase intermolecular inter- actions with planar aromatic guests. An additional interest of this new electron-rich clip relies on an excellent solubility in various solvents due to the presence of bulky 1,4-bis(tert-butyldiphenyl- silyloxy)ether groups, which prevent the usual dimeric packing preference of glycoluril-based molecular clips.17The nature of receptor1makes it a potentially versatile scaffold for studying donor and acceptor interactions between TTF and neutral electron-deficient guests. Highly efficient recognition properties of molecular clip 1 toward the neutral molecule tetrafluoro- tetracyanoquinodimethane (F4-TCNQ) are described.
Results and discussion
The synthesis of molecular clip1consists in using as a key-step the Diels–Alder cycloaddition between glycoluril–diquinone skeleton5acting as the bis-dienophile and 2,3-dimethylidene- [2H]TTF 7 playing the role of the diene (Scheme 2). First, compound4was prepared according to the literature18starting from known glycoluril derivative3by treatment with an excess of hydroquinone in 1,2-dichloroethane.19An aerial oxidation of compound 4 using CuCl as a catalyst in the presence of pyridine in DMSO solution was previously reported by Nolte and colleagues for the synthesis of compound5in 75% yield.15 We present here a new competitive method for the synthesis of 5by using DDQ as a dehydrogenation reagent of hydroquinone moieties.20 Reaction using DDQ was carried out in DMF to provide compound 5 in 65% yield, but this could be finally improved to reach 91% in THF instead of DMF.
Secondly, compound 5 was used as a bis-dienophile in a [4+2] cycloaddition reaction. Reductive elimination upon treat- ment of TTF derivative6with potassium iodide in the presence of 18-crown-6 gave risein situto transient diene7.21Following our experience in the efficient reactivity of such TTF-based diene22toward dienophiles such as fullerene C6023or quinone derivatives,24 the concomitant two Diels–Alder cycloadditions were carried out by trapping 2,3-dimethylidene-[2H]TTF7with bis-dienophile 5 at room temperature in THF. Under these experimental conditions, bis-cycloadduct 8 was not isolated and complete aromatization occurred subsequently, without using supplementary DDQ reagent. It should be noted that such a complete dehydrogenation phenomenon was previously observed when tetrakis(bromomethyl)benzene was reacted with 2,3-dimethylbenzoquinone in the presence of sodium iodide.25 Molecular clip1was isolated as a green powder in 20% yield after purification by column chromatography on silica gel using CH2Cl2/EtOAc (95 : 5) as the eluent. During our investigations around this Diels–Alder reaction, we observed that the aroma- tization could occur during the silica gel treatment. With the aim of improving the yield of this cycloaddition, we turned our attention to the replacement of potassium iodide with com- mercial iodo-ionic liquid BMI-I (1-butyl-3-methylimidazolium iodide) as the halogen source.26Unfortunately, despite a lot of efforts devoted to this reaction, we did not succeed in signifi- cantly improving the yield of molecular clip1(21% yield with BMI-I). 1H and 13C NMR spectra are in agreement with the achievement of molecular clip in the aromatized structure. The
1H spectrum of compound1(ESI†) showed the characteristic signals corresponding to the TTF-protected hydroquinone moieties, two doublets corresponding to the CH2–N glycoluril platform with an expected coupling constant (2J= 16.5 Hz), and finally, a singlet signal at 7.90 ppm corresponding to the protons resulting from the aromatization reaction. The MALDI-TOF mass spectrum exhibited the molecular peak thus confirming the aromatization of the molecular clip. Unfortunately, all attempts at growing single crystals of molecular clip 1 for X-ray diffraction studies have been unsuccessful so far. Consequently, theoretical calculations were realized using a semi-empirical AM1 method on molecular clip1without silylated groups on the hydroquinone moieties as a simplified model. The geometry optimization confirmed the expected quasi-planarity of the fused TTF-naphthoquinone unit constituting the arm of the molecular clip. The angleadefining the tapering cavity of the clip was determined to be close to 311 taking into account the two mean planes of the TTF-naphtho- quinone arms (Fig. 1). Moreover, the distance between both TTF central double bonds was estimated to be equal to 9.7 Å thus giving an estimation of the cavity size.
This system was shown to act as an effective receptor for neutral electron acceptors and the complexation ability of clip1 toward the neutral guest, such as F4-TCNQ, was evaluated by cyclic voltammetry and UV-Vis spectroscopy using electroche- mical and optical responses of both quinone and TTF units.
The electrochemical properties of molecular clip 1 were investigated by cyclic voltammetry (CV) in CH2Cl2/CH3CN (9/
1) solution usingn-Bu4NPF60.1 M as the electrolyte (Fig. 2). As 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55 Scheme 1 TTF and glycoluril-based molecular clips1and2.
Paper NJC
expected, the CV of molecular clip1showed two redox oxida- tion processes characteristic of the TTF moiety. These two one- electron oxidation waves atEox1= +0.67 V andEox2= +1.15 Vvs.
SCE correspond to the successive generation of the cation radical and dication of each TTF moiety, respectively (Fig. 1).
Whereas the first oxidation wave appears as a reversible pro- cess, the noticeable broader and non-reversible second redox wave could be assigned to inter-TTF interactions at the 14+
oxidized state. One reversible two-electron reduction process was shown for thep-benzoquinone (Q) moiety atEred1= 0.76 V
vs.SCE corresponding to the generation of the anion radical Q . Species on each acceptor unit. The coalescence of these reduction waves for both quinone units suggested that no effective electronic coupling between both Q centres occurred.27 The electrochemical detection of a neutral guest by using a redox-active host has attracted less attention with only a few examples reported in the literature compared to the more established detection of cations or anions.28We were interested 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55 Fig. 1 Geometry optimization of the analog of molecular clip1(without
silyl protecting groups of the hydroquinone units as a simplified model).
Fig. 2 Cyclic voltammogram for molecular clip1: 510 4M in CH2Cl2/ CH3CN (9/1) inn-Bu4NPF60.1 M. Pt as the working and counter electrode, Ag/Ag+reference electrode, scan rate 100 mV s 1. Values are givenvs.
SCE, the couple Fc/Fc+ (0.405 V vs. SCE) being used as an internal reference.
Scheme 2 Synthesis of molecular clip1.
This journal isc The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014 New J. Chem.,2014,00, 1 8 |3
NJC Paper
in using the cyclic voltammetry technique considering that the first oxidation and reduction waves of TTF and quinone, respectively, of the molecular clip constitute two possible signals to probe the recognition process.
Binding studies were performed by progressive addition of the F4-TCNQ acceptor to the solution of the receptor and determination of the binding was followed on both first oxida- tion or reduction waves of the clip and also on the reduction waves of the guest. Whereas no clear modification was observed on the first oxidation waves of TTF and F4-TCNQ units, a significant shift of the first reduction wave of the quinone unit to a less negative potential was observed, resulting from a more difficult reduction of the quinone moiety (Fig. 3).
The progressive addition of F4-TCNQ resulted in a positive shift of the first two-electron reduction wave of the quinone moiety withDEclose to 20 mV for one equivalent of F4-TCNQ (Fig. 4). This significant change in the electronic properties of the electroactive units of the molecular clip constitutes one of the few examples of neutral guest recognition evidenced by cyclic voltammetry.29
These results are in agreement with the electrostatic potential surface (EPS) of clip1determined by quantum chemical calculations using a B3LYP functional density approach with 6-31+G(2d,2p) basis
sets. The EPS was shown to be negative on both TTF arms and, hence, complementary to the EPS of the electron-deficient F4-TCNQ guest molecule (Fig. 5). Nevertheless, the strong negative EPS on the oxygen atoms of all carbonyl functions constituting the glycoluril–
diquinone scaffold should be noted.
The optical properties of molecular clip1were investigated using UV/Vis spectroscopy in 10 5 M solution in CH2Cl2. Compound5and silylated protected TTF-dihydroquinone 921 (Scheme 2) were used as references. Whereas the spectrum of the TTF derivative showed two absorption bands at 265 and 314 nm characteristic of the TTF core, a large absorption band between 350 and 450 nm could be attributed to an intra- molecular charge transfer interaction between conjugated TTF and quinone moieties in compound1. Moreover, the green color of clip1could be explained by the presence of a large but low intense absorption band (e= 1000 L mol 1cm 1) between 500 and 700 nm (Fig. 6).
The binding affinity of molecular clip 1 was studied by UV-Visible titration with the acceptor F4-TCNQ in CH2Cl2, which is characterized by an important absorption band at 386 nm. Addition of aliquots of molecular clip 1 in CH2Cl2 showed the formation and increase of bands at 760 and 860 nm which could be attributed to the progressive formation of the F4-TCNQ radical anion (Fig. 7).30 The increase of the band at around 625 nm was attributed to the cumulative contribution of the increasing amount of neutral clip1and the formation of 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55 Fig. 3 Cyclic voltammograms of molecular clip 1 [2.5 10 4 M in
CH2Cl2/CH3CN (9/1) in n-Bu4NPF6 0.1 M] upon addition of F4-TCNQ aliquots [10 2M in CH2Cl2/CH3CN (7/3)], scan rate: 100 mV s 1. The two reduction waves correspond to the second reduction wave of F4-TCNQ and the first reduction wave for the quinone moiety at 0.22 V and
0.76 Vvs.SCE, respectively.
Fig. 4 Plot of the shift of the first reductionEred1 of molecular clip1with added equivalents of F4-TCNQ.
Fig. 5 Electrostatic potential surfaces (EPS) of molecular clip1(left) and F4-TCNQ (right) showing that the electrostatic potential of the TTF arms is negative (shown in red), whereas the EPS of the F4-TCNQ guest molecule is calculated to be highly positive (shown in blue).
Fig. 6 UV-Visible absorption spectra of compounds 1 (black), 5 (red) and9(blue) in 10 5M CH2Cl2solution. In the inset, enlargement of the UV-Visible spectrum of compound1.
Paper NJC
TTF cation radical species. Chemical oxidation of molecular clip1in CH2Cl2solution was carried out by successive aliquot addition of NOSbF6 used as an oxidizing reagent, thus con- firming the absorption band of the TTF cation radical at around 625 nm (ESI).31
As can be seen in Fig. 8, the addition of F4-TCNQ resulted in an immediate color change of the CH2Cl2 solution from pale yellow-green to intense green, this observation being assignable to the formation of a charge-transfer complex.
This study of the electronic interaction between the TTF sidewalls of the receptor and the acceptor F4-TCNQ guest was complemented by 1H and 19F NMR spectra which also high- lighted the complexation of F4-TCNQ using receptor1(Fig. 9).
The1H NMR signal at 7.90 ppm, corresponding to the aromatic proton median between TTF and quinone units, gradually decreased then disappeared until the addition of one equivalent of F4-TCNQ guest. Similarly, the19F NMR signal characteristic of F4-TCNQ also disappeared (see full spectrum in the ESI†) when this guest was added in stoichiometric quantity to the molecular clip in CD2Cl2solution. This observation suggested the presence of a charge or electron transfer interaction between both electro- active TTF and F4-TCNQ units resulting in the generation of some paramagnetic species. Such rapid loss of the NMR 19F
signal of F4-TCNQ in CDCl3 has been recently reported when small amounts of regioregular poly(3-hexylthiophene) donor polymer were added. This phenomenon originated from the formation of minority paramagnetic species resulting from charge transfer and resulted in efficient doping of the polymer.32 Quantitative measurements were performed by monitoring the changes in the UV-Visible spectra at 860 nm of F4-TCNQ upon addition of sensor1(Fig. 10). To quantify the supramo- lecular host:guest interaction, the association constant was determined from this titration experiment.33 The association constantKa= 2.4104(0.1 104) M 1in CH2Cl2and the molar extinction coefficient of the complex (e = 975 20 L mol 1.cm 1) were calculated by the fit of the binding isotherm complexation curve performed with all the points of Fig. S10 (ESI†). Such a high binding value confirms that this rigidified molecular clip1is an efficient receptor for the F4-TCNQ acceptor, and this value has to be compared with the association constantKa= 5.6103(0.3103) M 1determined for interaction between molecular clip2and paraquat.16b
The construction of the corresponding Job plot corroborates with the 1 : 1 binding stoichiometry between clip 1 and F4-TCNQ with a maximum centered at a molar ratio of 0.5 (Fig. 11). This Job plot demonstrates that the phenomenon 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55 Fig. 7 UV-Visible absorption spectra of F4-TCNQ (CH2Cl2, 10 5M) upon
titration with molecular clip1(CH2Cl2, 510 4M). Inset: enlargement of the absorption spectra between 500 and 1000 nm.
Fig. 8 Visual color change of molecular clip1induced by the addition of F4-TCNQ: solutions in CH2Cl2(C= 2.510 4M) of molecular clip1(left), F4-TCNQ (centre) and clip: F4-TCNQ complex in 1 : 1 stoichiometry (right).
Fig. 9 Top: 1H NMR spectra (CD2Cl2) of molecular clip 1 (extension around 7.90 ppm) alone (A) and after addition of F4-TCNQ: 0.1 molar eq.
(B); 0.4 molar eq. (C); 1 molar eq. (D); bottom:19F NMR spectra (CD2Cl2) of F4-TCNQ alone (E) and after its addition to the molecular clip in the stoichiometry 1 : 1 molar (F).
This journal isc The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014 New J. Chem.,2014,00, 1 8 |5
NJC Paper
does not result from a redox reaction involving the exchange of one electron between TTF and F4-TCNQ. Indeed, given that both TTF units are oxidized to the cation radical state at the same potential, a Job plot with a 1 : 2 binding stoichiometry would have been obtained in such a hypothesis. This defini- tively confirms the inclusion of F4-TCNQ inside the cavity of the clip.
This result demonstrates that the size of the extended cavity presented here constitutes a fundamental parameter for binding the F4-TCNQ guest. For comparison, Nolte and colleagues have clearly shown using a glycoluril based receptor incorporating 2,7-dimethoxynaphthalene walls that steric effects play an important role. If the dimensions of the cavity of the clip are not sufficient, charge transfer complexes are obtained with TCNQ or TCNE but these acceptors are not bound in its cavity.15c Molecular clip1constitutes one of the rare examples of archi- tectures exhibiting good affinity for sandwiching F4-TCNQ as a prototypical electron-poor guest.34
Conclusions
In conclusion, an original and straightforward synthesis of glycoluril-based molecular clip including electroactive tetra- thiafulvalene sidewalls has been realized using an efficient
Diels–Alder cycloaddition approach. This rigid and preorganized molecular receptor is expected to display efficient sensing ability toward neutral guests. We showed strong binding with the acceptor F4-TCNQ in solution using cyclic voltammetry and UV-Visible titrations, giving a particular deeply coloured charge transfer complex. This result opens promising perspectives for designing and constructing a wide variety of novel receptor architectures. Binding studies with a wide variety of electron- poor guests using such electron-rich molecular clips are cur- rently underway.
Experimental
General methods
The following chemicals were obtained commercially and were used without any purification. Dry solvents were obtained by distillation over suitable desiccants (THF from Na/benzophe- none). Reactions were monitored by thin-layer chromatography on aluminium sheets coated with silica gel 60 F254. Flash chromatography was performed with silica gel 60A (40–60mm).
Melting points were determined using a Reichert-Jung micro- scope and are uncorrected.1H NMR and13C NMR spectra were recorded on Bruker Avance III 300 (1H: 300 MHz;13C: 75 MHz) spectrometer. Chemical shifts (d) are reported in ppm relative to residual CHCl3or CH2Cl2. IR spectra were recorded on a Bruker Vertex 70 spectrophotometer. UV-Visible experiments were performed using Perkin Elmer Lambda 19 NIR and 950 spectro- meters. Matrix-assisted laser-desorption/ionization mass spec- trometry was performed using a Bruker Daltonics BIFLEX III spectrometer by using dithranol as the matrix. The high resolu- tion mass spectrum (HRMS) was recorded using a LTQ Orbitrap (Thermo Scientific) under electrospray ionization (ESI) in posi- tive ionization mode. Cyclic voltammetry was carried out in a three-electrode cell equipped with a platinum millielectrode as the working electrode, a platinum wire counter electrode and a silver wire in a 0.01 M solution of AgNO3in CH3CN as a reference electrode. The electrolytic media involved a 0.1 M solution of tetra-n-butylammonium-hexafluorophosphate (TBAHP – puriss quality) in CH3CN. The ferrocene/ferrocenium couple (Fc/Fc+) was used as an internal reference and the potentials were expressedversusa saturated calomel electrode (SCE) as a refer- ence. All experiments were performed in a glove box containing dry, oxygen-free (o1 ppm) argon, at room temperature. Electro- chemical experiments were carried out using an EGG PAR 273A potentiostat.
Synthetic procedures Compound 5
Method A.To a solution of compound4(200 mg; 0.35 mmol) in THF (20 mL) was added DDQ (340 mg; 1.5 mmol). The reaction mixture was stirred at room temperature for 30 min under an argon atmosphere. After addition of water (20 mL), the reaction mixture was extracted with CH2Cl2. The organic layer was washed with water (320 mL), dried over MgSO4and the solvent was removed under vacuum. The residue was 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55 Fig. 10 UV-Visible titration curve obtained from titration of F4-TCNQ (C=
10 5M in CH2Cl2) with molecular clip1(C= 510 4M in CH2Cl2) at 860 nm.
Fig. 11 Job plot at 860 nm for F4-TCNQvs.molecular clip1at room temperature (C = 10 5 M in CH2Cl2) consistent with a 1 : 1 binding stoichiometry.
Paper NJC
purified by chromatography on silica gel (eluent: CH2Cl2) affording after precipitation using diethyl ether compound 5 as a pink powder (180 mg; 91% yield).
Method B.To a solution of compound4(185 mg, 0.33 mmol) in DMSO (5 mL) was added CuCl (25 mg, 0.25 mmol) and pyridine (0.25 mL). The solution was stirred for 2 h at room temperature with an air bubble in the solution. After addition of chloroform, the organic phase was successively washed with a 1 M HCl aqueous solution (50 mL) then 5% ammonia solution (250 mL), dried over MgSO4, and the solvent was removed under vacuum. The residue was purified by precipita- tion in a mixture of CH2Cl2 and petroleum ether to afford compound5(141 mg, 76%).
M.p 4 230 1C. 1H NMR (CDCl3) d: 7.14–7.17 (m, 6H, H phenyl), 6.98–7.01 (m, 4H, H phenyl), 6.74 (s, 4H, H quinone), 5.52 (d, 4H,2J= 16.5 Hz, CH2–N), 3.71 (d, 4H,2J= 16.5 Hz, CH2–N).
13C NMR (CDCl3) d: 185.4 (CQO), 157.4 (N–CQO), 141.7, 136.1, 131.5, 129.6, 129.3, 128.0, 85.6, 36.5. MS (ESI): [M + Na]+= 580.99 and [M + H]+= 559.02. IR (neat, cm 1):n~= 1727 (CQO amide), 1654 (CQO quinone), 1287 (C–N). HRMS for C32H22O6N4Na calcd:
581.14316; found: 581.14314.
Compound 1
Method A.To a solution of compound5a(100 mg, 0.18 mmol) in anhydrous THF (10 mL) were successively added a solution of 2,3-bis(bromomethyl)TTF6(300 mg, 0.32 mmol) in anhydrous THF (10 mL), 18-crown-6 (569 mg, 2.15 mmol) (freshly recrys- tallized in CH3CN), anhydrous KI (95 mg, 0.58 mmol). The reaction mixture was stirred for 24 h at room temperature under a nitrogen atmosphere. After addition of EtOAc, the solvent was partially concentrated under vacuum. The residue was purified by chromatography on silica gel (eluents CH2Cl2, then CH2Cl2/ EtOAc 95/5 then CH2Cl2/EtOAc 90/10) affording 75 mg com- pound 1bas a green powder in 20% yield. Compound 1was recrystallized in a CH2Cl2–pentane mixture of solvents.
Method B. 1-Butyl-3-methylimidazolium iodide (BMI-I) (750 mg, 2.8 mmol) was placed in a round bottom flask under an argon atmosphere. Compound5(100 mg, 0.18 mmol) and 2,3-bis(bromomethyl)TTF6(340 mg, 0.36 mmol) were added, and the solution was stirred at 601C for 72 h. After addition of CH2Cl2, the organic layer was washed with brine, dried over MgSO4, and the solvent was removed under vacuum. The residue was purified by using silica gel column chromatogra- phy (eluent: CH2Cl2) to afford compound1(80 mg, 21%).
1H NMR (CD2Cl2)d: 7.90 (s, 4H, Harom), 7.63 (m, 16H, Harom), 7.42–7.09 (m, 34H, Harom), 5.78 (s, 4H, Hhydroquinone), 5.62 (d, 4H,2J= 16.5 Hz, CH2–N), 3.72 (d, 4H,2J= 16.5 Hz, CH2–N), 1.09 (s, 36H, CH3).13C NMR (CD2Cl2)d: 182.3 (CQOquinone), 157.6 (CQOglycoluril), 145.3, 144.3, 144.1, 135.8, 132.5, 132.4, 132.3, 130.5, 129.8, 129.6, 129.5, 128.4, 128.2, 119.5, 116.4, 115.9, 107.0, 85.8, 36.7, 26.7, 19.7. MS: (MALDI-TOF, dithranol):
2126 (M+). IR (neat, cm 1):n~= 1719 (CQO ester), 1662 (CQO amide), 1258 (C–N), 1017 (C–O). HRMS for C120H102N4O10S8-
Si4Na: calcd: 2149.43309; found: 2149.42240.
Acknowledgements
This work was supported by the French National Research Agency in the frame of the program ANR PNANO entitled TTF-based Nanomat (ANR-07-NANO-030-01). We thank the French Ministry of Higher Education and Research for PhD grants to M. Hardouin-Lerouge and Y. Cotelle. We gratefully acknowledge Dr Ingrid Freuze (platform PIAM, University of Angers) for her assistance in mass spectrometry experiments.
Notes and references
1 J. W. Steed and J. L. Atwood,Supramolecular Chemistry, John Wiley & Sons Ltd, 2nd edn, 2009.
2 P. J. Cragg, Supramolecular principles for the mimicking of biologically important receptors, Springer, 2010.
3 (a) E. R. Kay, D. A. Leigh and F. Zerbetto,Angew. Chem., Int.
Ed., 2007,46, 72; (b) S. Saha and J. F. Stoddart,Chem. Soc.
Rev., 2007,36, 77; (c) Special Issue: Molecular Machines and Switches,Adv. Funct. Mater., 2007,17, 671.
4 (a) M. Hardouin-Lerouge, P. Hudhomme and M. Salle´,Chem.
Soc. Rev., 2011, 40, 30; (b) J. Leblond and A. Petitjean, ChemPhysChem, 2011, 12, 1043; (c) E. M. Pe´rez and N. Martı´n,Chem. Soc. Rev., 2008,37, 1512.
5 C.-W. Chen and H. W. Whitlock Jr.,J. Am. Chem. Soc., 1978, 100, 4921.
6 (a) S. C. Zimmerman and C. M. VanZyl,J. Am. Chem. Soc., 1987, 109, 7894; (b) S. C. Zimmerman, C. M. VanZyl and G. S.
Hamilton, J. Am. Chem. Soc., 1989, 111, 1373; (c) S. C.
Zimmerman, M. Mrksich and M. Baloga, J. Am. Chem. Soc., 1989,111, 8528; (d) S. C. Zimmerman,Top. Curr. Chem., 1993, 165, 71; (e) S. C. Zimmerman,Bioorg. Chem. Front., 1991,2, 33.
7 (a) F.-G. Kla¨rner, U. Burkert, M. Kamieth, R. Boese and J. Benet-Buchholz, Chem. – Eur. J., 1999,5, 1700; (b) F.-G.
Kla¨rner, J. Panitzky, D. Bla¨ser and R. Boese, Tetrahedron, 2001,57, 3673; (c) F.-G. Kla¨rner and B. Kahlert,Acc. Chem.
Res., 2003, 36, 919; (d) F.-G. Kla¨rner, B. Kahlert, R. Boese, D. Bla¨ser, A. Juris and F. Marchioni, Chem. – Eur. J., 2005, 11, 3363; (e) F. Marchioni, A. Juris, M. Lobert, U. P. Seelbach, B. Kahlert and F.-G. Kla¨rner,New J. Chem., 2005, 29, 780; (f) F.-G. Kla¨rner, B. Kahlert, A. Nellesen, J. Zienau, C. Ochsenfeld and T. Schrader,J. Am. Chem. Soc., 2006,128, 4831; (g) G. Fukuhara, S. Madenci, J. Polkowska, F. Bastkowski, F.-G. Kla¨rner, Y. Origane, M. Kaneda, T. Mori, T. Wada and Y. Inoue, Chem. – Eur. J., 2007, 13, 2473.
8 P. Batail, Molecular Conductors (Thematic issue), Chem.
Rev., 2004,104(11). Q4
9 D. Canevet, M. Salle´, G. Zhang, D. Zhang and D. Zhu,Chem.
Commun., 2009, 2245.
10 (a) J. L. Segura and N. Martı´n,Angew. Chem., Int. Ed., 2001, 40, 1372; (b)TTF Chemistry. Fundamentals and applications of tetrathiafulvalene, ed. J. Yamada and T. Sugimoto, Springer Verlag, 2004.
11 C. M. Davis, J. M. Lim, K. R. Larsen, D. S. Kim, Y. M. Sung, D. M. Lyons, V. M. Lynch, K. A. Nielsen, J. O. Jeppesen, 1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55
This journal isc The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2014 New J. Chem.,2014,00, 1 8 |7
NJC Paper
D. Kim, J. Su Park and J. L. Sessler,J. Am. Chem. Soc.
Q5 , 2014,
DOI: 10.1021/ja504077f.
12 T. Poulsen, K. A. Nielsen, A. D. Bond and J. O. Jeppesen,Org.
Lett., 2007,9, 5485.
13 M. H. Du¨ker, H. Scha¨fer, M. Zeller and V. A. Azov,J. Org.
Chem., 2013,78, 4905.
14 (a) V. A. Azov, R. Go´mez and J. Stelten,Tetrahedron, 2008, 64, 1909; (b) M. Skibin´ski, R. Go´mez, E. Lork and V. A. Azov, Tetrahedron, 2009,65, 10348.
15 (a) R. P. Sijbesma, S. S. Wijmenga and R. J. M. Nolte,J. Am.
Chem. Soc., 1992, 114, 9807; (b) R. P. Sijbesma, A. P. M. Kentgens, E. T. G. Lutz, J. H. van der Maas and R. J. M. Nolte, J. Am. Chem. Soc., 1993, 115, 8999;
(c) R. P. Sijbesma and R. J. M. Nolte,Top. Curr. Chem., 1995, 175, 25; (d) J. N. H. Reek, J. A. A. W. Elemans and R. J. M. Nolte, J. Org. Chem., 1997,62, 2234; (e) P. Polavarapu, H. Melander, V. Langer, A. Gogoll and H. Grennberg,New J. Chem., 2008, 32, 643; (f) N. She, M. Gao, L. Cao, A. Wu and L. Isaacs,Org.
Lett., 2009, 11, 2603; (g) S. Ghosh, A. Wu, J. C. Fettinger, P. Y. Zavalij and L. Isaacs,J. Org. Chem., 2008,73, 5915.
16 (a) P.-N. Chen, P.-T. Chiang and S.-H. Chiu,Chem. Commun., 2005, 1285; (b) P.-T. Chiang, P.-N. Chen, C.-F. Lin, Y.-H. Liu, C.-C.
Lai, S.-M. Peng and S.-H. Chiu,Chem. – Eur. J., 2006,12, 865.
17 Z.-G. Wang, B.-H. Zhou, Y.-F. Chen, G.-D. Yin, Y.-T. Li, A.-X. Wu and L. Isaacs,J. Org. Chem., 2006,71, 4502.
18 J. W. H. Smeets, R. P. Sijbesma, L. van Dalen, A. L. Speck, W. J. J. Smeets and R. J. M. Nolte, J. Org. Chem., 1989, 54, 3710.
19 (a) A. R. Butler and I. Hussain,J. Chem. Soc., Perkin Trans. 2, 1981, 310; (b) R. P. Sijbesma, W. P. Bosnian and R. J. M. Nolte,J. Chem. Soc., Chem. Commun., 1991,13, 885.
20 (a) D. Walker and J. D. Hiebert,Chem. Rev., 1967,67, 153;
(b) F. Dumur, N. Gautier, N. Gallego-Planas, Y. S-ahin, E. Levillain, N. Mercier, P. Hudhomme, M. Masino, A. Girlando, V. Lloveras, J. Vidal-Gancedo, J. Veciana and C. Rovira,J. Org. Chem., 2004,69, 2164.
21 J. Baffreau, F. Dumur and P. Hudhomme,Org. Lett., 2006, 8, 1307.
22 P. Hudhomme, S.-G. Liu, D. Kreher, M. Cariou and A. Gorgues,Tetrahedron Lett., 1999,40, 2927.
23 (a) C. Boulle, J.-M. Rabreau, P. Hudhomme, M. Cariou, M. Jubault, A. Gorgues, J. Orduna and J. Garı´n,Tetrahedron
Lett., 1997, 38, 3909; (b) P. Hudhomme, C. Boulle, J.-M. Rabreau, M. Cariou, M. Jubault and A. Gorgues,Synth.
Met., 1998, 94, 73; (c) D. Kreher, S.-G. Liu, M. Cariou, P. Hudhomme, A. Gorgues, M. Mas, J. Veciana and C. Rovira, Tetrahedron Lett., 2001, 42, 3447; (d) S.-G. Liu, D. Kreher, P. Hudhomme, E. Levillain, M. Cariou, J. Delaunay, A. Gorgues, J. Vidal-Gancedo, J. Veciana and C. Rovira, Tetrahedron Lett., 2001,42, 3717; (e) D. Kreher, M. Cariou, S.-G. Liu, E. Levillain, J. Veciana, C. Rovira, A. Gorgues and P. Hudhomme, J. Mater. Chem., 2002, 12, 2137; (f) A. Gorgues, P. Hudhomme and M. Salle´,Chem.
Rev., 2004,104, 5151; (g) P. Hudhomme,C. R. Chim., 2006, 9, 881.
24 (a) C. Boulle, O. Desmars, N. Gautier, P. Hudhomme, M. Cariou and A. Gorgues, Chem. Commun., 1998, 2197;
(b) N. Gautier, N. Mercier, A. Riou, A. Gorgues and P. Hudhomme,Tetrahedron Lett., 1999,40, 5997.
25 A. D. Thomas and L. L. Miller,J. Org. Chem., 1986,51, 4160.
26 C. P. Be´nard, Z. Geng, M. A. Heuft, K. VanCrey and A. G. Fallis,J. Org. Chem., 2007,72, 7229.
27 N. Gautier, F. Dumur, V. Lloveras, J. Vidal-Gancedo, J. Veciana, C. Rovira and P. Hudhomme, Angew. Chem., Int. Ed., 2003,42, 2765.
28 (a) P. D. Beer, P. A. Gale and G. Z. Chen,Coord. Chem. Rev., 1999,185–186, 3; (b) J. S. Park, F. Le Derf, C. M. Bejger, V. M. Lynch, J. L. Sessler, K. A. Nielsen, C. Johnsen and J. O. Jeppesen,Chem. – Eur. J., 2010,16, 848.
29 S. Goeb, D. Canevet and M. Salle´, inOrganic Synthesis and Molecular Engineering, ed. M. O. Nielsen, Wiley, 2013, ch. 8, p. 213.
30 A. Jain, K. V. Rao, U. Mogera, A. A. Sagade and S. J. George, Chem. – Eur. J., 2011,17, 12355.
31 V. Khodorkovsky, L. Shapiro, P. Krief, A. Shames, G. Mabon, A. Gorgues and M. Giffard,Chem. Commun., 2001, 2736.
32 J. Gao, E. T. Niles and J. K. Grey,J. Phys. Chem. Lett., 2013, 4, 2953.
33 (a) H. Hirose,J. Inclusion Phenom. Macrocyclic Chem., 2001, 39, 193; (b) H. Hirose, inAnalytical methods in supramole- cular chemistry, ed. C. Schalley, Wiley, 2007, ch. 2, p. 17;
(c) P. Thordarson,Chem. Soc. Rev., 2011,40, 1305.
34 S. Bivaud, J.-Y. Balandier, M. Chas, M. Allain, S. Goeb and M. Salle´,J. Am. Chem. Soc., 2012,134, 1196.
1
5
10
15
20
25
30
35
40
45
50
55
1
5
10
15
20
25
30
35
40
45
50
55
Paper NJC
