Manuscripta Medica Tom. III

Pp. 141-176 Table, with 4 columns: (from interior of page) running number, author of experiment, short description, and keywords of experiment

Synthesis and Supramolecular Assembly of Pentacyclic Dithienofluorene and Diselenophenofluorene Derivatives

2,7-Diiodo-3,6-dibromofluorene and 2,7-dichloro-3,6-dibromofluorene have been successfully synthesized. The two key intermediates enable us to implement a regioselective Sonogashira reaction followed by intramolecular thiolate/acetylene cyclization, forming two regiospecific pentacyclic dithieno­[2,3-<i>b</i>:7,6-<i>b</i>′]­fluorene (<b>2,7-DTF</b>) and dithieno­[3,2-<i>b</i>:6,7-<i>b</i>′]­fluorene (<b>3,6-DTF</b>) isomeric molecules, respectively. By using a similar strategy, selenophene-based diselenopheno­[2,3-<i>b</i>:7,6-<i>b</i>′]­fluorene (<b>2,7-DSF</b>) as well as diselenopheno­[3,2-<i>b</i>:6,7-<i>b</i>′]­fluorene (<b>3,6-DSF</b>) were also prepared. The isomeric and sulfur/selenium effects determine the optical, electrochemical, and orbital properties. X-ray crystallography revealed that <b>2,7-DTF</b> and <b>3,6-DTF</b> molecules assemble into supramolecular helical structures

Intuitive Quantifiers of Charge Flows in Coordinate Bonding

ETS–NOCV charge and bond energy analyses have been carried out for a broad range of transition-metal carbonyl complexes L–[M], comprising different ligand classes, transition metals, and coordination geometries. The resulting electronic redistributions are visually assigned to σ donation, π backbonding, and related interactions. We propose a Hirshfeld partitioning of these electronic redistributions to afford the corresponding charge flow contributions Δ<i>q</i>_σ, Δ<i>q</i>_π, etc. Taken together, a detailed picture of the dative bonding arises, in terms of both energetics and the extent of σ-electron donation and π-electron backbonding. The charge flows Δ<i>q</i>_σ and Δ<i>q</i>_π appropriately quantify trends in the ligand σ-donor and π-acceptor abilities and are transferable across the transition-metal complexes studied and thus promise to be suitable descriptors for ligand knowledge bases. As a case in point, the TEP is well reproduced by the calculated ν_CO(A₁) frequencies and is 3 times more strongly affected by Δ<i>q</i>_σ than by Δ<i>q</i>_π, with an additional modest steric influence. Further, empirical relationships are derived among the charge flows Δ<i>q</i>_σ and Δ<i>q</i>_π, the (L)­W­(CO)₅ carbonyl stretching frequencies, and the ligand’s steric volume %<i>V</i>_bur, which allow estimating the σ-donor and π-acceptor abilities of phosphines from experimental observables. On the other hand, direct Cl:→L−σ* interactions are identified in several <i>cis</i>-(L)­Ir­(CO)₂Cl complexes, which compromises the use of these species as experimental probes for ligand parameters

Intuitive Quantifiers of Charge Flows in Coordinate Bonding

ETS–NOCV charge and bond energy analyses have been carried out for a broad range of transition-metal carbonyl complexes L–[M], comprising different ligand classes, transition metals, and coordination geometries. The resulting electronic redistributions are visually assigned to σ donation, π backbonding, and related interactions. We propose a Hirshfeld partitioning of these electronic redistributions to afford the corresponding charge flow contributions Δ<i>q</i>_σ, Δ<i>q</i>_π, etc. Taken together, a detailed picture of the dative bonding arises, in terms of both energetics and the extent of σ-electron donation and π-electron backbonding. The charge flows Δ<i>q</i>_σ and Δ<i>q</i>_π appropriately quantify trends in the ligand σ-donor and π-acceptor abilities and are transferable across the transition-metal complexes studied and thus promise to be suitable descriptors for ligand knowledge bases. As a case in point, the TEP is well reproduced by the calculated ν_CO(A₁) frequencies and is 3 times more strongly affected by Δ<i>q</i>_σ than by Δ<i>q</i>_π, with an additional modest steric influence. Further, empirical relationships are derived among the charge flows Δ<i>q</i>_σ and Δ<i>q</i>_π, the (L)­W­(CO)₅ carbonyl stretching frequencies, and the ligand’s steric volume %<i>V</i>_bur, which allow estimating the σ-donor and π-acceptor abilities of phosphines from experimental observables. On the other hand, direct Cl:→L−σ* interactions are identified in several <i>cis</i>-(L)­Ir­(CO)₂Cl complexes, which compromises the use of these species as experimental probes for ligand parameters

Synthesis of Poly(3-hexylthiophene), Poly(3-hexylselenophene), and Poly(3-hexylselenophene-<i>alt</i>-3-hexylthiophene) by Direct C–H Arylation Polymerization via <i>N</i>‑Heterocyclic Carbene Palladium Catalysts

Direct C–H arylation polymerization of 2-bromo-3-hexylselenophene and 2-bromo-3-hexylthiophene catalyzed by <i>N</i>-heterocyclic carbene (NHC) palladium-based and Pd­(OAc)₂-based systems has been carried out and investigated. Under the optimized conditions, high molecular weight poly­(3-hexylthiohphene) (P3HT) (<i>M</i>_n = 26.9K g/mol) with high head-to-tail regioregularity (94%) can be obtained by using [1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene]­chloro­[3-phenylallyl]­palladium­(II) (Pd-IPr) as the catalyst. Pd-IPr exhibits a wide range of working temperatures from 70 to 140 °C and good catalytic reproducibility as a result of its high thermal stability. It was found that the presence of additional phosphine ligand, such as tris­(<i>o</i>-methoxyphenyl)­phosphine, can increase the polymerization efficiency in the Pd­(OAc)₂ system. This improvement is linked to the stability enhancement for the active species during the course of catalysis. For the first time, poly­(3-hexylselenophene) (P3HS) was also obtained by direct-arylation polymerization in this research. The modest molecular weight is attributed to the poor solubility of P3HS in the used solvents. Density-functional-theory (DFT) calculations were performed to investigate the postulated reaction mechanisms for our catalytic systems. The experimental observations can thus be elucidated by the help of computation. Most significantly, a main-chain alternating and side-chain regioregular (RR = 94%) poly­(3-hexylselenophene-<i>alt</i>-3-hexylthiophene) (Alt-P3HST) with high molecular weight (20.0K g/mol) was successfully synthesized via the Pd-IPr-catalyzed direct-arylation polymerization of a well-designed 2-bromo-3-hexyl-5-(3-hexylselenophen-2-yl)­thiophene monomer. The molecular properties of the Alt-P3HST were characterized to compare with those of P3HT and P3HS. This research demonstrates in-depth investigation on the NHC-based palladium catalysts for the synthesis of conjugated polymers via direct C–H bond polymerization

Angular-Shaped 4,10-Dialkylanthradiselenophene and Its Donor–Acceptor Conjugated Polymers: Synthesis, Physical, Transistor, and Photovoltaic Properties

An angular-shaped and isomerically pure 4,10-di­(2-octyl)­dodecyl­anthradiselenophene (aADS) was successfully developed. The expedient synthesis to form the framework of aADS with two lateral side chains regioselectively at its 4,10-positions is via a base-induced propargyl–allenyl isomerization/6π-electrocyclization/aromatization protocol. This pentacyclic distannylated aADS unit was then copolymerized with dithienyl­diketopyrrolopyrrole (DPP) and dithienyl-5,6-difluoro-2,1,3-benzothiadiazole (DTFBT) acceptors with different alkyl side chains to afford four donor–acceptor copolymers: PaADSDPP, PaADSDTFBT-C₄, PaADSDTFBT-C₈, and PaADSDTFBT-C₈C₁₂. UV–vis spectroscopy and cyclic voltammetry revealed that PaADSDPP has the narrowest energy band gap, and PaADSDTFBT-C₈C₁₂ has larger band gap than PaADSDTFBT-C₄ and PaADSDTFBT-C₈. Two layer ONIOM (our own <i>n</i>-layered integrated molecular orbital and molecular mechanics) calculations were implemented to investigate the disparity in optical, electrochemical, and device properties between these polymers. Both experimental and theoretical data suggest that the aliphatic side chains play a significant role in determining the physical, transistor, and photovoltaic properties of the polymers. PaADSDTFBT-C₄ and PaADSDTFBT-C₈ exhibited organic-field-effect-transistor hole mobilities of 2.7 × 10^–2 and 1.0 × 10^–2 cm² V^–1 s^–1, greatly outperforming that of PaADSDTFBT-C₈C₁₂ with a mobility of 5.4 × 10^–6 cm² V^–1 s^–1. Polymer solar cells were fabricated on the basis of ITO/PEDOT:PSS/polymer:PC₇₁BM/Ca/Al configuration. The efficiency decreased as the increase of bulkiness of the aliphatic side chains installed on DTFBT units (4.4% for PaADSDTFBT-C₄, 3.5% for PaADSDTFBT-C₈, 0.3% for PaADSDTFBT-C₈C₁₂). Atomic force microscopy images reveal that the degree of aggregation for the polymer:fullerene blends is influenced significantly by the bulkiness of aliphatic side chain installed on DTFBT. Noticeable aggregation was found for the PaADSDTFBT-C₈C₁₂:PC₇₁BM blend. These results are in good agreement with the computational results elucidating that the intermolecular interactions between the polymers and PC₇₁BM are sterically hindered by the bulky 2-octyldodecyl groups. This work not only presents a promising selenophene-based aADS building block but also provides insights into the side-chain engineering for donor–acceptor conjugated copolymers

Synthesis and Molecular Properties of Two Isomeric Dialkylated Tetrathieno­naphthalenes

Isomeric 2,8-distannyl 5,11-didodecyl αβ-TTN (<b>1</b>, tetrathienonaphthalene = TTN) and 2,8-didodecyl 5,11-distannyl αβ-TTN (<b>2</b>) have been designed and successfully synthesized. The naphthalene core structures in αβ-TTNs were constructed by a systematic protocol using PtCl₂-catalyzed cyclization followed by oxidative Scholl annulation in good yields. Compared to the one-dimensional naphthodithiophene derivatives, the two-dimensional αβ-TTN molecules showed good solubility, extended conjugation, strong absorptivity, and highly coplanar structures. Compounds <b>1</b> and <b>2</b> were polymerized with a 5,5′-dibromo-2,2′-bithiophene-based monomer to afford 2,8-αβ-PTTNTT and 5,11-αβ-PTTNTT copolymers. 2,8-αβ-PTTNTT with the α-aNDT moiety in the main chain exhibited a higher hole mobility of 1.26 × 10^–2 cm² V^–1 s^–1

Synthesis and Molecular Properties of Two Isomeric Dialkylated Tetrathieno­naphthalenes

Isomeric 2,8-distannyl 5,11-didodecyl αβ-TTN (<b>1</b>, tetrathienonaphthalene = TTN) and 2,8-didodecyl 5,11-distannyl αβ-TTN (<b>2</b>) have been designed and successfully synthesized. The naphthalene core structures in αβ-TTNs were constructed by a systematic protocol using PtCl₂-catalyzed cyclization followed by oxidative Scholl annulation in good yields. Compared to the one-dimensional naphthodithiophene derivatives, the two-dimensional αβ-TTN molecules showed good solubility, extended conjugation, strong absorptivity, and highly coplanar structures. Compounds <b>1</b> and <b>2</b> were polymerized with a 5,5′-dibromo-2,2′-bithiophene-based monomer to afford 2,8-αβ-PTTNTT and 5,11-αβ-PTTNTT copolymers. 2,8-αβ-PTTNTT with the α-aNDT moiety in the main chain exhibited a higher hole mobility of 1.26 × 10^–2 cm² V^–1 s^–1

Synthesis and Molecular Properties of Four Isomeric Dialkylated Angular-Shaped Naphthodithiophenes

A new strategy to synthesize 4,9- and 5,10-dialkylated α-aNDTs as well as 4,9- and 5,10-dialkylated β-aNDTs is described. Four isomeric precursors with different dithienyl-ene-diyne arrangements undergo base-induced double 6π-cyclization to construct the central naphthalene cores, leading to the formation of the regiospecific products. These 2,7-distannylated dialkylated aNDT-based monomers can be used for Stille cross-coupling to produce promising conjugated materials for various optoelectronic applications

Synthesis and Isomeric Effects of Ladder-Type Alkylated Terbenzodithiophene Derivatives

A new class of heptacyclic ladder-type terbenzodithiophene (TBDT) structures merging three fused benzodithophenes was developed. Two TBDT conjugated isomers, named as <i>syn</i>-TBDT and <i>anti</i>-TBDT, where the two thienyl rings in the outmost BDT units are in the <i>syn</i>- and <i>anti</i>-fashion, are designed. Two decyl groups are introduced to their 6,13 and 7,14-positions to form four isomeric 6,13-<i>syn</i>-TBDT, 7,14-<i>syn</i>-TBDT, 6,13-<i>anti</i>-TBDT, and 7,14-<i>anti</i>-TBDT structures which are constructed by the DBU-induced 6-benzannulation involving propargyl-allenyl isomerization of the dieneyne moieties in the corresponding precursors followed by 6π-electrocyclization/aromatization, while isomeric TD-<i>syn</i>-TBDT and TD-<i>anti</i>-TBDT with four decyl groups substituted at 6,7,13,14-positions are synthesized via palladium-catalyzed dialkylacetylene insertion/C–H arylation of the corresponding iodobiaryl precursors. The intrinsic properties can be modulated by molecular manipulation of the main-chain and side-chain isomeric structures. <i>anti</i>-TBDT derivatives exhibit higher melting points, larger bandgaps, stronger intermolecular interactions, and higher mobility than the corresponding <i>syn</i>-TBDT analogues. These molecules can be further utilized as building blocks to make various TBDT-based materials for optoelectronic applications