Weak interactions in the assembly of strongly chemisorbed molecules

Goubert, Guillaume; Demers-Carpentier, Vincent; Masini, Federico; Dong, Yi; Lemay, Jean‐Christian; McBreen, Peter H.

doi:10.1039/c1cc12538a

Cited by 5 publications

(6 citation statements)

References 20 publications

(26 reference statements)

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“…Columns of PhDPP and TDPP pack in a herringbone arrangement, whereas PhTDPP forms lamellar stacks (Figure ). The herringbone arrangement of PhDPP and TDPP allows for an interaction between the aromatic protons of one column with the carbonyl groups of adjacent columns. , Additionally, T-shaped edge-to-face aromatic interactions are observed in PhDPP between neighboring columns . In the case of PhTDPP, there are also interactions between the thiophene 4-protons and the carbonyl groups of adjacent molecules (Figure S2).…”

Section: Resultsmentioning

confidence: 99%

Effects of Crystal Morphology on Singlet Exciton Fission in Diketopyrrolopyrrole Thin Films

Hartnett¹,

Margulies²,

Mauck³

et al. 2016

J. Phys. Chem. B

141

241

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Singlet exciton fission (SF) is a promising strategy for increasing photovoltaic efficiency, but in order for SF to be useful in solar cells, it should take place in a chromophore that is air-stable, highly absorptive, solution processable, and inexpensive. Unlike many SF chromophores, diketopyrrolopyrrole (DPP) conforms to these criteria, and here we investigate SF in DPP for the first time. SF yields in thin films of DPP derivatives, which are widely used in organic electronics and photovoltaics, are shown to depend critically on crystal morphology. Time-resolved spectroscopy of three DPP derivatives with phenyl (3,6-diphenylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione, PhDPP), thienyl (3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione, TDPP), and phenylthienyl (3,6-di(5-phenylthiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione, PhTDPP) aromatic substituents in 100-200 nm thin films reveals that efficient SF occurs only in TDPP and PhTDPP (τSF = 220 ± 20 ps), despite the fact that SF is most exoergic in PhDPP. This result correlates well with the greater degree of π-overlap and closer π-stacking in TDPP (3.50 Å) and PhTDPP (3.59 Å) relative to PhDPP (3.90 Å) and demonstrates that SF in DPP is highly sensitive to the electronic coupling between adjacent chromophores. The triplet yield in PhTDPP films is determined to be 210 ± 35% by the singlet depletion method and 165 ± 30% by the energy transfer method, showing that SF is nearly quantitative in these films and that DPP derivatives are a promising class of SF chromophores for enhancing photovoltaic performance.

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Section: Resultsmentioning

confidence: 99%

Effects of Crystal Morphology on Singlet Exciton Fission in Diketopyrrolopyrrole Thin Films

Hartnett¹,

Margulies²,

Mauck³

et al. 2016

J. Phys. Chem. B

141

241

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“…Based on surface-science studies under UHV [88][89][90], adsorption of the modifier on the metal has been proposed to occur through the aromatic ring. Extensive work by McBreen and coworkers, mainly relying on surface imaging using STM but also using vibrational spectroscopies, have provided nice experimental evidence for the formation of hydrogen-bonded complexes between NEA and a number of model reactants on platinum single-crystal surfaces [91][92][93][94][95][96][97][98][99][100].…”

Section: One-to-one Chiral Modifiersmentioning

confidence: 99%

Surface Chemistry for Enantioselective Catalysis

2014

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A Perspective is offered on the lessons learned from surface-science studies on enantioselective chemistry on solid surfaces performed by the author's groups. Our emphasis is on studies on model systems, mainly metal single-crystal surfaces under controlled environments, but extension of such research to more realistic samples relevant to heterogeneous catalysis is also briefly discussed. Enantioselective chemistry on surfaces is here divided into three guiding modalities, depending on the underlying mechanism. First, enantioselective chemistry resulting from the use of intrinsically chiral surfaces, which can be made from achiral solids such as metals by exposing the appropriate planes, is discussed. Next, the imparting of enantioselectivity to achiral surfaces by modifying them with adsorbates is classified in terms of two operating mechanisms: first, via the formation of supramolecular surface ensembles with chiral adsorption sites, and second, by relying on the effect of the local chiral environment intrinsically provided by the chiral modifiers through a one-to-one interaction between the modifier and the reactant. A discussion is then provided on studies with more complex samples involving metal nanoparticles and highsurface-area porous oxides. Finally, the present state of our understanding of enantioselective surface chemistry and the prognosis for the future are provided.

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“…The STM image 3F matches our previously reported images for vinylnaphthalene formed by the partial dehydrogenation of ethyl naphthalene on Pt(111). 12 As illustrated in Scheme 2B, vinylnaphthalene could result from scission of a C−N bond in adsorbed PNEA, followed by the expected 12,13 partial dehydrogenation of the alkyl substitutent to yield adsorbed vinylnapthalene. The accompanying adsorbed fragment formed by CN bond scission would then be an aminolactone species (Scheme 2A).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Aminolactone Chiral Modifiers for Heterogeneous Asymmetric Hydrogenation: Corrected Structure of Pantoyl-Naphthylethylamine, In-Situ Hydrogenolysis, and Scanning Tunneling Microscopy Observation of Supramolecular Aminolactone/Substrate Assemblies on Pt(111)

et al. 2013

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As established by Baiker and co-workers, pantoylnaphthylethylamine (PNEA) is an efficient synthetic chiral modifier for the asymmetric hydrogenation of ketopantolactone (KPL) to pantolactone on supported Pt catalysts. We report a scanning tunneling microscopy (STM) study of PNEA and PNEAderived aminolactone species on Pt(111) and a reassignment of the relative stereochemistry of the modifier. Robust organic chemistry methods were used to establish that the structure of PNEA is R,S rather than R,R. The dissociative chemisorption of a fraction of PNEA adsorbed on Pt(111) yields two fragments that we attribute to a process involving C−N bond scission. We show that C−N bond scission occurs under hydrogenation conditions on PNEA-modified Pt/Al 2 O 3 catalysts, forming the aminolactone amino-4,4-dimethyldihydrofuran-2-one (AF). STM measurements on (S)-AF and 2,2,2-trifluoroacetophenone coadsorbed on Pt(111) show the formation of isolated 1:1 complexes. In contrast, measurements on coadsorbed (S)-AF and KPL show fluxional supramolecular AF/KPL assemblies. The possibility that such assemblies contribute to the overall enantioselectivity observed for PNEA-modified Pt catalysts is discussed.

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Weak interactions in the assembly of strongly chemisorbed molecules

Abstract: The intermolecular structure of bimolecular complexes formed on Pt(111) at room temperature through CH···O interactions between 1-methylnaphthalene or 1-ethylnaphthalene and 2,2,2-trifluoroacetophenone is directed by the partial dehydrogenation of the alkyl groups.

Cited by 5 publications

References 20 publications

Effects of Crystal Morphology on Singlet Exciton Fission in Diketopyrrolopyrrole Thin Films

Effects of Crystal Morphology on Singlet Exciton Fission in Diketopyrrolopyrrole Thin Films

Surface Chemistry for Enantioselective Catalysis

Aminolactone Chiral Modifiers for Heterogeneous Asymmetric Hydrogenation: Corrected Structure of Pantoyl-Naphthylethylamine, In-Situ Hydrogenolysis, and Scanning Tunneling Microscopy Observation of Supramolecular Aminolactone/Substrate Assemblies on Pt(111)

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