Influence of Fluorene and Spirobifluorene Regioisomerism on the Structure, Organization, and Permeation Properties of Monolayers

Abstract

ABSTRACT.9,9'-Spirobifluorene (SBF) and Fluorene derivatives are extensively used as active layer in many organic electronic devices nowadays, thus careful examination of their structure and organization in thin films and monolayers are of primary importance. In the present work, immobilization of SBF and Fluorene isomers was performed via Click Chemistry coupling reaction onto well- 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 2 significant impact of their positional isomerism on the monolayers structuration was clearly evidenced. Indeed, 2-substituted SBF and Fluorene monolayers appear to be more compact and ordered than their 4-substituted analogues, and are orientated parallel to the surface. These findings should have an important impact on the construction and performances of SBF and Fluorene based organic electronic devices.

A post-functionalization toolbox for diazonium (electro)-grafted surfaces: review of the coupling methods

“…114 These azide-or alkyne-modified surfaces react efficiently and rapidly with compounds bearing an acetylene or an azide function respectively, thus forming a covalent 1,2,3triazole linkage by means of click chemistry. This approach, compatible with a myriad of electroactive groups, has been exploited to immobilize ferrocene, 105, porphyrin, 142 phthalocyanin, 113,[143][144][145][146] tetrathiafulvalene, 147 fluorene, 148,149 BODIPY, 150,151 metallic complexes, 85,[152][153][154] TEMPO 155 or nitrophenyl derivatives. 138 The role of the redox probe varies according to the nature of the studies undertaken.…”

“…Whether they are carried out in one direction or another (azide surface and alkyne in solution, or the opposite), the couplings are made under similar operating conditions. Cupper(I) is always used as a reaction catalyst (directly added, 134,148,162,173,175 or formed in situ from cupper(II) and a reducing agent 85,105,[113][114][115]119,[121][122][123][124]127,128,132,135,139,140,142,147,149,157,158,160,[163][164][165][166]168,177,178 or electrochemically generated 137,176 ). The most common option relies on the combined use of copper(II) sulfate and ascorbic acid (or sodium ascorbate, usually in excess) as reducing agent.…”

New generations of spirobifluorene regioisomers for organic electronics: tuning electronic properties with the substitution pattern

“…[7][8][9] New electronic applications taken advantages of the cross-shape geometry of the SBF fragment have also started to appear in the literature such as non-fullerene acceptors in solar cells, [10][11][12][13] spiro-fused nanographene structures 14 or ordered monolayers. 15,16 Thanks to this singular geometry, the SBF scaffold has also been investigated for other appealing applications outside of organic electronics such as fluorescent marker for biomolecules, 17 chiral ligands, 18,19 catalysts in homogeneous 20, 21 or heterogeneous [21][22][23][24] chemical reactions (epoxidation, sulfoxidation…), or as building units in coordination polymers, 25,26 showing the versatility of this platform. In all these examples, it is the 3D geometry of the SBF scaffold that has been taken advantage of.…”

Cyclization of Terphenyl‐Bisfluorenols: A Mechanistic Study of the Regioselectvity

“…One can cite for example heterogeneous and homogeneous catalysis (e.g. epoxidation, cyclopropanation), coordination polymers, or surfaces modification …”

“…epoxidation, cyclopropanation), [24][25][26][27][28][29] coordination polymers, [30] or surfaces modification. [31] From as ynthetic point of view,g enerating spiro-configured compounds [32] and especially differently substituted spirobifluorenes (SBF) is usually performed through intramolecular electrophilic cyclization of af luoren-9-ol in the presence of a Lewis or aB rønsted acid (Scheme 1). [3,[33][34][35][36] If the pendant phenylr ing of the biphenyl core is substituted at its para position the intramolecular cyclization stepl eads to as ingle product, that is, 2-substituted-spirobifluorene being hence regioselective (Scheme 1-top).H owever,i ft he pendantp henyl unit is substituted at its meta position, the electrophilica ttack may occur on two different positions leadingt ot he formationo f two regioisomers (1-and 3-substitutedS BF [23] ), hence being non-regioselective.…”