전자 증여체와 수용체로 쓰이는 파이렌 유도체 연구

학위논문 (박사)-- 서울대학교 대학원 : 화학부, 2015. 8. 손병혁.약 200 년 전에 파이렌이 최초로 발견되었고, 그 이후로 이 물질은 전 세계의 화학자들에게 끊임없는 관심을 받아왔다. 파이렌에 관한 수많은 화학 연구 분야 중, 선택적 기능화는 큰 조명을 받아온 분야 중 하나이다. 왜냐하면 분자의 다른 위치들에 특정한 기능화를 하는 것은 현재까지도 굉장히 어려운 주제이기 때문이다. 이번 논문에서는 파이렌 치환의 두가지 새로운 양식들을 개발하였다. 적절한 조건에서 4,5,9,10-tetramethoxypyrene 의 네 겹의 브롬화는 여덟 겹으로 기능화된 파이렌들의 생산을 가능하게 해준다. 위와 같은 분자들을 기반으로 1,3,4,5,6,7,9,10 위치가 치환된 새로운 파이렌 파생물들을 얻을 수 있다. Non-quinoidal 합성법은 전자 수용체의 중간체에 적절하게 적용될 수 있었지만, 전자가 거의 없는 파이렌 파생물을 얻는 데는 실패하였다. 또한, 전자 증여체로써의 4,5,9,10-tetramethoxypyrene 도 합성되었고, 위 물질들의 전하 이동 복합체로서의 역할에 관한 연구를 진행하였다. 고체 상태에서 SFB/RT 49 을 통해 위 복합체들을 분석하였고, non-TTF CT-complex 에서의 전하이동을 HAXPES 와 NEXAFS 를 통해 연구하였다. Zöphel 외 두 명의 연구를 기반으로 비대칭의 4,9,10 위치가 치환된 파이렌 파생물을 얻을 수 있다. 이것은 판형이 아닌 전자 수용체 분자에 더하여 전자가 풍푸한 파이렌 타입의 분자들을 합성하기 위한 블록으로 사용되었다. 마지막으로 두가지 분리된 구조의 분자들이 유기발광소자의 발광체로 사용되었다. 유기발광소자 중 열활성화 지연형광은 형광 유기발광소자의 효율을 증진시킬 수 있는 획기적인 방법으로 학계의 큰 관심을 받고 있다. 이번 연구에서 합성한 물질들은 굉장히 깊은 청색 발광을 가지면서 동시에 높은 형광 발광 효율을 유지하면서 단일상태와 삼중상태의 에너지 차이가 최소가 되도록 설계되었다. 초기의 OD 시리즈들은 굉장히 작은 에너지 차이를 가졌지만 유기 발광소자에 사용하기에는 불충분한 절대 발광 효율을 가지고 있었다. 반대로 파이렌 시리즈들은 앞의 두 가지 특성들을 동시에 반족시킴으로써, 효율이 좋은 유기발광소자에 발광체로 효과적으로 적용되었다.I. Introduction 1 I.1 Pyrene 1 I.2 Organic semiconducting materials 13 I.3 Organic light emitting diodes (OLEDs) 19 I.4 Objects and motivation 24 II. Functionalization of pyrene in positions 2 and 7 ... 29 II.1 Electron deficient materials 30 II.2 Electron-rich materials 48 II.3 Summary 55 III. Functionalization of pyrene in positions 1,3,6 and 8... 59 III.1 The 1,3,6,8-functionalization of 4,5,9,10-substituted pyrenes 60 III.2 Electron rich materials 70 III.3 Electron deficient materials 85 III.4 Summary and outlook 103 IV. Charge-transfer complexes 107 IV.1 Donor ? acceptor interactions 107 IV.2 New CT-complexes 108 IV.3 CT-complexes studied in the context of the SFB/TR 49 ...120 IV.4 ??????????????Summary 134 ??V. Emitters for thermally delayed fluorescence in OLEDs 135 ?V.1 Introduction 135 ?V.2 Molecular design 135 ?V.3 Synthesis 141 ?V.4 Characterization 146 ?V.5 Summary 169 VI. Functionalization of pyrene in the positions 4,9 and 10 ...171 VI.1 [4,4'-Bipyrene]-9,9',10,10'-tetraone (6-6) 172 ??????VI.2 New rylene-type molecules 175 VI.3 Summary and outlook 179 VII. Conclusion 183 VIII. Experimental Section 187 VIII.1 General methods 187 VIII.2 Analytical methods 188 VIII.3 Synthesis 191 VIII.4 Crystallographic data 236 IX. Bibliography 248 X. List of publications 261 XI. Acknowledgement 263 XII. Curriculum vitae 265 국문초록 267Docto

Comparing charge transfer tuning effects by chemical substitution and uniaxial pressure in the organic charge transfer complex tetramethoxypyrene-tetracyanoquinodimethane

In the search for novel organic charge transfer salts with variable charge transfer degree we study the effects of two modifications to the recently synthesized donor-acceptor Tetramethoxypyrene (TMP)-Tetracyanoquinodimethane (TCNQ). One is of chemical nature by substituting the acceptor TCNQ molecules by F4TCNQ molecules. The second consists in simulating the application of uniaxial pressure along the stacking axis of the system. In order to test the chemical substitution, we have grown single crystals of TMP-F4TCNQ and analyzed its electronic structure via electronic transport measurements, ab initio density functional theory (DFT) calculations and UV/VIS/IR absorption spectroscopy. This system shows an almost ideal geometrical overlap of nearly planar molecules alternately stacked (mixed stack) and this arrangement is echoed by a semiconductor-like transport behavior with an increased conductivity along the stacking direction. This is in contrast to TMP-TCNQ which shows a less pronounced anisotropy and a smaller conductivity response. Our bandstructure calculations confirm the one-dimensional behavior of TMP-F4TCNQ with pro- nounced dispersion only along the stacking axis. Infrared measurements illustrating the CN vibration frequency shift in F4TCNQ suggest however no improvement on the degree of charge transfer in TMP-F4TCNQ with respect to TMP-TCNQ. In both complexes about 0.1 is transferred from TMP to the acceptor. Concerning the pressure effect, our DFT calculations on designed TMP-TCNQ and TMP-F4TCNQ structures under different pressure conditions show that application of uniaxial pressure along the stacking axis of TMP-TCNQ may be the route to follow in order to obtain a much more pronounced charge transfer

A new charge-transfer complex in UHV co-deposited tetramethoxypyrene and tetracyanoquinodimethane

UHV-deposited films of the mixed phase of tetramethoxypyrene and tetracyanoquinodimethane (TMP1-TCNQ1) on gold have been studied using ultraviolet photoelectron spectroscopy (UPS), X-ray-diffraction (XRD), infrared (IR) spectroscopy and scanning tunnelling spectroscopy (STS). The formation of an intermolecular charge-transfer (CT) compound is evident from the appearance of new reflexes in XRD (d1= 0.894 nm, d2= 0.677 nm). A softening of the CN stretching vibration (red-shift by 7 cm-1) of TCNQ is visible in the IR spectra, being indicative of a CT of the order of 0.3e from TMP to TCNQ in the complex. Characteristic shifts of the electronic level positions occur in UPS and STS that are in reasonable agreement with the prediction of from DFT calculations (Gaussian03 with hybrid functional B3LYP). STS reveals a HOMO-LUMO gap of the CT complex of about 1.25 eV being much smaller than the gaps (>3.0 eV) of the pure moieties. The electron-injection and hole-injection barriers are 0.3 eV and 0.5 eV, respectively. Systematic differences in the positions of the HOMOs determined by UPS and STS are discussed in terms of the different information content of the two methods.Comment: 20 pages, 6 figure

Extended π-conjugated pyrene derivatives: structural, photophysical and electrochemical properties

This article presents a set of extended π-conjugated pyrene derivatives, namely 1,3-di(arylethynyl)-7-tert-butylpyrenes, which were synthesized by a Pd-catalyzed Sonogashira coupling reaction of 1,3-dibromo-7-tert-butylpyrenes with the corresponding arylethynyl group in good yields. Despite the presence of the tert-butyl group located at the 7-position of pyrene, X-ray crystallographic analyses show that the planarity of the Y-shaped molecules still exhibits strong face-to-face π-π stacking in the solid state; all of the compounds exhibit blue or green emission with high quantum yields (QYs) in dichloromethane. DFT calculations and electrochemistry revealed that this category of compound possesses hole-transporting characteristics. In addition, with strong electron-donating (-N(CH₃)₂) or electron-withdrawing (-CHO) groups in 2 d or 2 f, these molecules displayed efficient intramolecular charge-transfer (ICT) emissions with solvatochromic shifts from blue to yellow (green) on increasing the solvent polarity. Furthermore, the compounds 2 d and 2 f possess strong CT characteristics

Functionalization of Pyrene To Prepare Luminescent Materials—Typical Examples of Synthetic Methodology

Pyrene-based π-conjugated materials are considered to be an ideal organic electro-luminescence material for application in semiconductor devices, such as organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaics (OPVs), and so forth. However, the great drawback of employing pyrene as an organic luminescence material is the formation of excimer emission, which quenches the efficiency at high concentration or in the solid-state. Thus, in order to obtain highly efficient optical devices, scientists have devoted much effort to tuning the structure of pyrene derivatives in order to realize exploitable properties by employing two strategies, 1) introducing a variety of moieties at the pyrene core, and 2) exploring effective and convenient synthetic strategies to functionalize the pyrene core. Over the past decades, our group has mainly focused on synthetic methodologies for functionalization of the pyrene core; we have found that formylation/acetylation or bromination of pyrene can selectly lead to functionalization at K-region by Lewis acid catalysis. Herein, this Minireview highlights the direct synthetic approaches (such as formylation, bromination, oxidation, and de-tert-butylation reactions, etc.) to functionalize the pyrene in order to advance research on luminescent materials for organic electronic applications. Further, this article demonstrates that the future direction of pyrene chemistry is asymmetric functionalization of pyrene for organic semiconductor applications and highlights some of the classical asymmetric pyrenes, as well as the latest breakthroughs. In addition, the photophysical properties of pyrene-based molecules are briefly reviewed. To give a current overview of the development of pyrene chemistry, the review selectively covers some of the latest reports and concepts from the period covering late 2011 to the present day

Pyrene derivatives as donors and acceptors

Pyrene derivatives as donors and acceptorsrnrnAlmost 200 years have passed since pyrene was first discovered, and to this day it garners unbroken interest by chemists around the world. One of the most fascinating areas of pyrene chemistry is its selective functionalization, since it is still currently a challenge to specifically functionalize different positions on the molecule.[1]rnIn this work, two new patterns of pyrene substitution have been developed. Under suitable conditions, a fourfold bromination of 4,5,9,10 tetramethoxypyrene is possible to yield eightfold functionalized pyrenes. Based on these molecules a novel series of 1,3,4,5,6,8,9,10-substituted pyrene derivatives was achieved. Synthetic approaches to a non-quinoidal, strong pyrene-4,5,9,10-tetraone based acceptor have been discussed. It emerged that the chosen synthetic approach is suitable for intermediate acceptors, yet it failed very electron deficient pyrene derivatives. Donors based on 4,5,9,10-tetramethoxypyrene (2,7- and 1,3,6,8-substitued) have been prepared and studied as CT complexes. In the SFB/TR 49 these complexes were analyzed in the solid state. For the first time charge transfer in a non-TTF CT-complex was studied by HAXPES and NEXAFS.rnBased on the works of ZÖPHEL et al.[2] it was possible to obtain an asymmetric 4,9,10 substituted pyrene derivative. This was used as a building block to prepare a non-planar acceptor molecule as well as electron-rich rylene-type molecules. rnFinally, two separate series of molecules intended as emitters for OLEDs were presented. Thermally activated delayed fluorescence (TADF) in OLEDs attracted significant academic interest as it is considered a promising approach to improve the efficiency of fluorescent OLEDs.[3] Our molecules were designed to have a deep blue emission spectrum and a minimal singlet triplet energy gap (∆ES1->T1) while retaining a high fluorescence quantum yield ϕPL. The initial OD series has a small ∆ES1->T1, yet had an insufficient ϕPL for the use in OLEDs. The Py series emitters, in contrast, combine both desired properties and were successfully implemented in efficient OLED devices.rn[1]. T. M. Figueira-Duarte and K. Müllen, Chem. Rev., 2011, 111, 7260-7314.rn[2]. L. Zöphel, V. Enkelmann and K. Müllen, Org. Lett., 2013, 15, 804-807.rn[3]. H. Uoyama, K. Goushi, K. Shizu, H. Nomura and C. Adachi, Nature, 2012, 492, 234-238.Pyrene derivatives as donors and acceptorsrnrnVor fast 200 Jahren wurde Pyren das erste Mal beschrieben. Bis heute arbeiten weltweit Chemiker an der Erforschung dieses aromatischen Kohlenwasserstoffs. Seine selektive Funktionalisierung stellt auch weiterhin eine faszinierende Herausforderung da, wobei noch immer nicht alle Positionen selektiv adressiert werden können. [1]rnIn dieser Arbeit wurden zwei neue Substitutionsmuster für Pyren entwickelt. Die Bedingungen für eine vierfache Bromierung von 4,5,9,10-Tetramethoxypyren wurden entwickelt um eine Serie von 1,3,4,5,6,8,9,10-funktionalisierten Pyrenderivaten zu erhalten. Syntheseansätze für sehr starke nicht-chinoide Akzeptoren wurden diskutiert. Hierbei erwies sich der gewählte Syntheseansatz nur geeignet für schwache und mittel-starke Akzeptoren. Sehr starke Akzeptoren konnten nicht erhalten werden. Zudem wurden ausgehend von 4,5,9,10-Tetramethoxypyren eine Reihe elektronenreicher Verbindungen dargestellt und diese in charge-transfer(CT)-Komplexen untersucht. Diese Komplexe wurden im Rahmen des SFB/TR49 für Festkörperanalysen zur Verfügung gestellt. Es konnten zum ersten Mal der Elektronenübergang in einem TTF-freien CT-Komplex mittels HAXPES und NEXAFS untersucht werden.rnBasierend auf den Arbeiten von ZÖPHEL et al.[2] konnte ein unsymmetrisches Pyren Derivat erhalten werden. Dies wurde als Baustein für einen nicht-planaren Akzeptor sowie einer Reihe Rylen-artiger Moleküle verwendet. rnrnAbschließend wurden zwei Kandidaten (OD Serie und Py Serie) als OLED Emitter untersucht. Thermally activated delayed fluorescence (TADF) gilt als vielversprechender Ansatz für die Effizienzsteigerung in Fluoreszenz-OLEDs.[3] Von den Kandidaten wurde erwartet eine blaue Fluoreszenz mit einer kleinen singulet-triplett Energielücke (∆ES1->T1) und einer hohen Fluoreszenzquantenausbeute ϕPL miteinander zu verbinden. Die OD Serie wies eine kleine Energielücke auf, jedoch war ϕPL nicht ausreichend für den Einsatz in Leuchtdioden. Hingen gelang es mit der Py Serie alle Anforderungen an ein Emitter Material zu vereinen und dieses in effizienten Leuchtdioden einzusetzen.rn[1]. T. M. Figueira-Duarte and K. Müllen, Chem. Rev., 2011, 111, 7260-7314.rn[2]. L. Zöphel, V. Enkelmann and K. Müllen, Org. Lett., 2013, 15, 804-807.rn[3]. H. Uoyama, K. Goushi, K. Shizu, H. Nomura and C. Adachi, Nature, 2012, 492, 234-238