- Enantioselective adsorption in homochiral metal-organic frameworks: The pore size influence
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Uptake experiments in thin films of isoreticular chiral MOFs of type Cu2(Dcam)2(L) with identical stereogenic centers but different pore dimensions show that the enantioselectivity is significantly influenced by the pore size. The hi
- Gu, Zhi-Gang,Grosjean, Sylvain,Br?se, Stefan,W?ll, Christof,Heinke, Lars
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- One-Pot Synthesis and Redox Properties of Conjugation-Extended 4,4'-Bipyridines and Related Compounds. New Ligands Consisting of a Heterocyclic Three-Ring Assembly
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Dipyridyl-substituted heterocycles such as 2,5-di(4-pyridyl)thiophene 3, 2,5-di(4-pyridyl)furan 4, 2,5-di(4-pyridyl)thienothiophene 7, 1,4-di(4-pyridyl)benzene 6, 2,5-di(2-pyridyl)thiophene 8, and 2,5-di(3-pyridyl)thiophene 9 have been efficiently
- Takahashi, Kazuko,Nihira, Takayasu
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- Achieving a rare breathing behavior in a polycatenated 2 D to 3 D net through a pillar-ligand extension strategy
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Through a pillar-ligand extension strategy, a rare breathing behavior in polycatenated 2D→3D nets has been achieved. Three variants exhibit interesting sorption properties that range from non-breathing to breathing behaviors, which is influenced by the angles between the pillars and the single honeycomb layers. The increase in pillar length does not lead to an increase in polycatenation multiplicity, which is controlled by the length of intralayer tripodal carboxylate. It also does not induce obviously expanded interlayer separations but occupies much more the free voids, and as a consequence, a smaller pore volume is obtained. This suggests that in 2D→3D polycatenated bilayer metal-organic frameworks, the porosity is not always enhanced by increasing the length of the interlayer pillars with the intralayer linker remaining unchanged. Copyright
- Zhao, Xiaoliang,Liu, Fuling,Zhang, Liangliang,Sun, Di,Wang, Rongming,Ju, Zhangfeng,Yuan, Daqiang,Sun, Daofeng
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- Viologen Derivatives Extended with Aromatic Rings Acting as Negative Electrode Materials for Use in Rechargeable Molecular Ion Batteries
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Many types of batteries have been proposed as next-generation energy-storage systems. One candidate is a rocking-chair-type “molecular ion battery” in which a molecular ion, instead of Li+, works as a charge carrier. Previously, we reported a viologen-type derivative as a negative electrode material that releases and receives PF6? anions during the charge–discharge process; however, its redox potential was not satisfactorily low. Further, the two potential plateaus of this material (difference=0.5 V) should be reduced. In this study, PF6? salts of viologen (bipyridinium) derivatives extended by aromatic rings were synthesized to obtain a negative electrode material with a lower redox potential and small potential change during the charge and discharge processes. Some of the synthesized viologen derivatives were fluorescent even in solid-state electrodes. In the half-cell configuration, the prepared negative electrode materials showed average voltages of approximately 2 V (vs. Li+/Li), which is lower than that of conventional viologen derivatives.
- Kato, Minami,Sano, Hikaru,Kiyobayashi, Tetsu,Yao, Masaru
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- Chemical control of spin propagation between heterometallic rings
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We present a synthetic, structural, theoretical, and spectroscopic study of a family of heterometallic ring dimers which have the formula [{Cr 7NiF3(Etglu)(O2CtBu)15} 2(NLN)], in which Etglu is the pentadeprotonated form of the sugar N-ethyl-D-glucamine, and NLN is an aromatic bridging diimine ligand. By varying NLN we are able to adjust the strength of the interaction between rings with the aim of understanding how to tune our system to achieve weak magnetic communication between the spins, a prerequisite for quantum entanglement. Micro-SQUID and EPR data reveal that the magnetic coupling between rings is partly related to the through-bond distance between the spin centers, but also depends on spin-polarization mechanisms and torsion angles between aromatic rings. Density functional theory (DFT) calculations allow us to make predictions of how such chemically variable parameters could be used to tune very precisely the interaction in such systems. For possible applications in quantum information processing and molecular spintronics, such precise control is essential.
- Faust, Thomas B.,Bellini, Valerio,Candini, Andrea,Carretta, Stefano,Lorusso, Giulia,Allan, David R.,Carthy, Laura,Collison, David,Docherty, Rebecca J.,Kenyon, Jasbinder,MacHin, John,McInnes, Eric J. L.,Muryn, Christopher A.,Nowell, Harriott,Pritchard, Robin G.,Teat, Simon J.,Timco, Grigore A.,Tuna, Floriana,Whitehead, George F. S.,Wernsdorfer, Wolfgang,Affronte, Marco,Winpenny, Richard E. P.
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- Eliminating the need for independent counterions in the construction of metal-organic rotaxane frameworks (MORFs)
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The combination of a disulfonated-dibenzo-24crown-8 ether wheel and a dicationic 1,2-bis(pyridinium)ethane axle yields a neutral [2]pseudorotaxane which in combination with neutral metallic units such as a Cu(ii)benzoate paddlewheel or Cu(i)Br unit yields
- Knight, Lisa K.,Vukotic, V. Nicholas,Viljoen, Elizabeth,Caputo, Christopher B.,Loeb, Stephen J.
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- Palladium(O)/LiCl Promoted Cross-Coupling Reaction of (4-Pyridyl)stannanes and Aromatic Bromides: Easy Access to Poly(4-pyridyl)-Substituted Aromatics
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A PdCl2(PPh3)2/LiCl catalyst effectively promoted the cross-coupling reaction of trimethyl(4-pyridyl)stannane and aromatic polybromides to offer easy access to poly(4-pyridyl)-substituted aromatic compounds.
- Fujita, Makoto,Oka, Hiroko,Ogura, Katsuyuki
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- ExBox: A polycyclic aromatic hydrocarbon scavenger
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A template-directed protocol, which capitalizes on donor-acceptor interactions, is employed to synthesize a semi-rigid cyclophane (ExBox 4+) that adopts a box-like geometry and is comprised of π-electron-poor 1,4-phenylene-bridged ("extended") bipyridinium units (ExBIPY2+). ExBox4+ functions as a high-affinity scavenger of an array of different polycyclic aromatic hydrocarbons (PAHs), ranging from two to seven fused rings, as a result of its large, accommodating cavity (approximately 3.5 A? in width and 11.2 A? in length when considering the van der Waals radii) and its ability to form strong non-covalent bonding interactions with π-electron-rich PAHs in either organic or aqueous media. In all, 11 PAH guests were observed to form inclusion complexes with ExBox4+, with coronene being the largest included guest. Single-crystal X-ray diffraction data for the 11 inclusion complexes ExBox 4+?PAH as well as UV/vis spectroscopic data for 10 of the complexes provide evidence of the promiscuity of ExBox4+ for the various PAHs. Nuclear magnetic resonance spectroscopy and isothermal titration calorimetric analyses of 10 of the inclusion complexes are employed to further characterize the host-guest interactions in solution and determine the degree with which ExBox4+ binds each PAH compound. As a proof-of-concept, a batch of crude oil from Saudi Arabia was subjected to extraction with the water-soluble form of the PAH receptor, ExBox·4Cl, resulting in the isolation of different aromatic compounds after ExBox·4Cl was regenerated.
- Barnes, Jonathan C.,Jurí?ek, Michal,Strutt, Nathan L.,Frasconi, Marco,Sampath, Srinivasan,Giesener, Marc A.,McGrier, Psaras L.,Bruns, Carson J.,Stern, Charlotte L.,Sarjeant, Amy A.,Stoddart, J. Fraser
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- ExTzBox: A Glowing Cyclophane for Live-Cell Imaging
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The ideal fluorescent probe for live-cell imaging is bright and non-cytotoxic and can be delivered easily into the living cells in an efficient manner. The design of synthetic fluorophores having all three of these properties, however, has proved to be challenging. Here, we introduce a simple, yet effective, strategy based on well-established chemistry for designing a new class of fluorescent probes for live-cell imaging. A box-like hybrid cyclophane, namely ExTzBox·4X (6·4X, X = PF6-, Cl-), has been synthesized by connecting an extended viologen (ExBIPY) and a dipyridyl thiazolothiazole (TzBIPY) unit in an end-to-end fashion with two p-xylylene linkers. Photophysical studies show that 6·4Cl has a quantum yield φF = 1.00. Furthermore, unlike its ExBIPY2+ and TzBIPY2+ building units, 6·4Cl is non-cytotoxic to RAW 264.7 macrophages, even with a loading concentration as high as 100 μM, presumably on account of its rigid box-like structure which prevents its intercalation into DNA and may inhibit other interactions with it. After gaining an understanding of the toxicity profile of 6·4Cl, we employed it in live-cell imaging. Confocal microscopy has demonstrated that 64+ is taken up by the RAW 264.7 macrophages, allowing the cells to glow brightly with blue laser excitation, without any hint of photobleaching or disruption of normal cell behavior under the imaging conditions. By contrast, the acyclic reference compound Me2TzBIPY·2Cl (4·2Cl) shows very little fluorescence inside the cells, which is quenched completely under the same imaging conditions. In vitro cell investigations underscore the significance of using highly fluorescent box-like rigid cyclophanes for live-cell imaging.
- Roy, Indranil,Bobbala, Sharan,Zhou, Jiawang,Nguyen, Minh T.,Nalluri, Siva Krishna Mohan,Wu, Yilei,Ferris, Daniel P.,Scott, Evan Alexander,Wasielewski, Michael R.,Stoddart, J. Fraser
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- {[Ru(bda)]:XLy}n cross-linked coordination polymers: Toward efficient heterogeneous catalysis for water oxidation in an organic solvent-free system
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Recently, the development of polymeric catalysts for water splitting has received an increasing amount of attention. In this study, we successfully developed a few novel cross-linked coordination polymers (CCPs) with the formula {[Ru(bda)]xLy}n as efficient heterogeneous catalysts for water oxidation in an organic solvent-free system, where Ru(bda) represents the catalytic center. Detailed water oxidation catalytic kinetics studies suggested that single-site water nucleophilic attack (WNA) is the general mechanism applied to these polymeric catalysts, which is different to the small-molecular reference, [Ru(bda)(pic)2] (pic = 4-picoline). The experimental evidence also indicated the importance of interfacial wettability and the existence of the Ru(bda)-macrocyclic fragments in the polymer network in determining the overall catalytic activity. More interestingly, end-capping modification via the pyridine/DMSO exchange reaction further removed the residual Ru(DMSO)x moieties on the surfaces of the polymer network, which leads to the improved performance with an impressive TOF of ～4.6 s-1 and TON of ～750 in an organic solvent-free system, which are superior to [Ru(bda)(pic)2]. The rate of catalysis is among the highest for a heterogeneous system reported to date. An electrochemical study showed the polymeric catalysts were also promising electrode materials for electrocatalytic water oxidation and an electrode based on CCP/Nafion/ITO maintained ～73% of its initial activity after 27 cycles under the optimal conditions.
- Zheng, Tao,Li, Lianwei
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- Efficient and Rapid Mechanochemical Assembly of Platinum(II) Squares for Guanine Quadruplex Targeting
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We present a rapid and efficient method to generate a family of platinum supramolecular square complexes, including previously inaccessible targets, through the use of ball milling mechanochemistry. This one-pot, two-step process occurs in minutes and enables the synthesis of the squares [Pt4(en)4(N∩N)4][CF3SO3]8 (en= ethylenediamine, N∩N = 4,4′-bipyridine derivatives) from commercially available precursor K2PtCl4 in good to excellent yields. In contrast, solution-based assembly requires heating the reagents for weeks and gives lower yields. Mechanistic investigations into this remarkable rate acceleration revealed that solution-based assembly (refluxing for days) results in the formation of large oligomeric side-products that are difficult to break down into the desired squares. On the other hand, ball milling in the solid state is rapid and appears to involve smaller intermediates. We examined the binding of the new supramolecular squares to guanine quadruplexes, including oncogene and telomere-associated DNA and RNA sequences. Sub-micromolar binding affinities were obtained by fluorescence displacement assays (FID) and isothermal titration calorimetry (ITC), with binding preference to telomere RNA (TERRA) sequences. ITC showed a 1:1 binding stoichiometry of the metallosquare to TERRA, while the stoichiometry was more complex for telomeric quadruplex DNA and a double-stranded DNA control.
- Garci, Amine,Castor, Katherine J.,Fakhoury, Johans,Do, Jean-Louis,Di Trani, Justin,Chidchob, Pongphak,Stein, Robin S.,Mittermaier, Anthony K.,Fri??i?, Tomislav,Sleiman, Hanadi
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- Versatile Tailoring of Paddle-Wheel ZnII Metal-Organic Frameworks through Single-Crystal-to-Single-Crystal Transformations
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A new tetracarboxylate ligand having short and long arms formed 2D layer ZnII coordination polymer 1 with paddle-wheel secondary building units under solvothermal conditions. The framework undergoes solvent-specific single crystal-to-single crystal (SC-SC) transmetalation to produce 1Cu. With a sterically encumbered dipyridyl linker, the same ligand forms non-interpenetrated, 3D, pillared-layer ZnII metal-organic framework (MOF) 2, which takes part in SC-SC linker-exchange reactions to produce three daughter frameworks. The parent MOF 2 shows preferential incorporation of the longest linker in competitive linker-exchange experiments. All the 3D MOFs undergo complete SC-SC transmetalation with CuII, whereby metal exchange in different solvents and monitoring of X-ray structures revealed that bulky solvated metal ions lead to ordering of the shortest linker in the framework, which confirms that the solvated metal ions enter through the pores along the linker axis.
- Pal, Tapan K.,Neogi, Subhadip,Bharadwaj, Parimal K.
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- Construction of non-interpenetrated charged metal-organic frameworks with doubly pillared layers: Pore modification and selective gas adsorption
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The rigid and angular tetracarboxylic acid 1,3-bis(3,5-dicarboxyphenyl) imidazolium (H4L+), incorporating an imidazolium group, has been used with different pyridine-based linkers to construct a series of non-interpenetrated cationic frameworks, {[Zn2(L)(bpy) 2]·(NO3)·(DMF)6·(H 2O)9}n (1), {[Zn2(L)(dpe) 2]·(NO3)·(DMF)3·(H 2O)2}n (2), and {[Zn2(L)(bpb) 2]·(NO3)·(DMF)3·(H 2O)4}n (3) [L = L3-, DMF = N,N′-dimethylformamide, bpy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene, bpb = 1,4-bis(4-pyridyl)benzene]. The frameworks consist of {[Zn2(L)]+}n two-dimensional layers that are further pillared by the linker ligands to form three-dimensional bipillared-layer porous structures. While the choice of the bent carboxylic acid ligand and formation of double pillars are major factors in achieving charged non-interpenetrated frameworks, lengths of the pillar linkers direct the pore modulation. Accordingly, the N2 gas adsorption capacity of the activated frameworks (1a-3a) increases with increasing pillar length. Moreover, variation in the electronic environment and marked difference in the pore sizes of frameworks permit selective CO2 adsorption over N2, where 3a exhibits the highest selectivity. In contrast, the selectivity of CO2 over CH4 is reversed and follows the order 1a > 2a > 3a. These results demonstrate that even though the pore sizes of the frameworks are large enough compared to the kinetic diameters of the excluded gas molecules, the electronic environment is crucial for the selective sorption of CO2.
- Sen, Susan,Neogi, Subhadip,Aijaz, Arshad,Xu, Qiang,Bharadwaj, Parimal K.
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- Structural variation in Zn(ii) coordination polymers built with a semi-rigid tetracarboxylate and different pyridine linkers: Synthesis and selective CO2 adsorption studies
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In an effort towards the rational design of porous MOFs with a functionalized channel surface, 3,3′,5,5′- tetracarboxydiphenylmethane (H4L1) has been used in combination with two different bipyridine ligands of similar lengths as lin
- Sen, Susan,Neogi, Subhadip,Aijaz, Arshad,Xu, Qiang,Bharadwaj, Parimal K.
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- The difference in the CO2adsorption capacities of different functionalized pillar-layered metal-organic frameworks (MOFs)
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The excessive use of fossil energy has caused the CO2concentration in the atmosphere to increase year by year. MOFs are ideal CO2adsorbents that can be used in CO2capture due to their excellent characteristics. Studies of the structure-activity relationship between the small structural differences in MOFs and the CO2adsorption capacities are helpful for the development of efficient MOF-based CO2adsorbents. Therefore, a series of pillar-layered MOFs with similar structural and different functional groups were designed and synthesized. The CO2adsorption tests were carried out at 273 K to explore the relationship between the small structural differences in MOFs caused by different functional groups and the CO2adsorption capacities. Significantly, compound6which contains a pyridazinyl group has a 30.9% increase in CO2adsorption capacity compared to compound1with no functionalized group.
- Gao, Xiang-Jing,Zheng, He-Gen
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supporting information
p. 9310 - 9316
(2021/07/12)
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- Viologen derivative, preparation method thereof and electrochromic device
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The invention provides a viologen derivative and a preparation method thereof and further provides an electrochromic device. The electrochromic device comprises an electrolyte solution, wherein the electrolyte solution contains the viologen derivative and
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Paragraph 0089-0091; 0095
(2019/12/12)
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- Diverse Multi-Functionalized Oligoarenes and Heteroarenes for Porous Crystalline Materials
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A modular synthesis of multi-functionalized biphenyl, terphenyl and higher linear oligophenylene dicarboxylic acids and pyridine-terminated oligoarenes by stepwise palladium–catalyzed borylation/Suzuki–Miyaura cross-coupling reactions is described. The presence of several distinct functional groups such as azide, hydroxy, and alkyne, as well as coordinative functional end groups (carboxylic acid or pyridine) combined in a single oligoarene molecular unit at strategic positions offer an advantageous dual-utility. First, these compounds can serve as useful molecular bricks (ditopic organic linkers) in the construction of complex porous crystalline materials. Second, after the assembly into the crystalline coordination networks, orthogonal functional sites within the linker-backbone offer tremendous potential from application perspectives as they can be modified by a wide range of post-synthetic modifications including azide–alkyne click chemistry. This allows further tailoring of the supramolecular assemblies to yield novel multifunctional materials.
- Grosjean, Sylvain,Hassan, Zahid,W?ll, Christof,Br?se, Stefan
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p. 1446 - 1460
(2018/10/24)
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- Modular supramolecular dimerization of optically tunable extended aryl viologens
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Cucurbit[8]uril (CB[8]) mediated assembly of extended aryl viologens (EVs) into optically tunable dimers is reported for the first time. We show that the modular design and synthesis of a new class of π-conjugated viologen derivatives with rigid aromatic
- Olesińska, Magdalena,Wu, Guanglu,Gómez-Coca, Silvia,Antón-García, Daniel,Szabó, Istvan,Rosta, Edina,Scherman, Oren A.
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p. 8806 - 8811
(2019/10/16)
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- ELECTROCHROMIC COMPOUNDS AND OPTICAL ARTICLES CONTAINING THEM
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Electrochromic compounds and optical articles containing them The present invention relates to a group of novel electrochromic compounds. More specifically, it relates to electrochromic compounds comprising one or several pyridinium rings and the use of these compounds as a variable transmittance medium for the manufacture of an optical article, such as an ophthalmic lens.
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Paragraph 0117
(2018/07/31)
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- Efficient Suzuki-Miyaura mono-arylation of symmetrical diiodo(hetero)arenes
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A reliable protocol for converting 1,4-diiodo-2,3,5,6-tetrafluorobenzene into 1-(hetero)aryl-4-iodo-2,3,5,6-tetrafluorobenzene derivatives has been lacking in the literature. We have identified optimal conditions to achieve this conversion in good yields and have minimized formation of the bis-coupling product. The newly identified protocol involving the use of a syringe pump has been extended to other symmetrical diiodo(hetero)arenes.
- Sapegin, Alexander,Krasavin, Mikhail
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supporting information
p. 1948 - 1951
(2018/04/16)
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- Two fluorescent cyclopalladated arylpyrazine complexes: synthesis, crystal structures and application in the double Suzuki coupling of N-heteroaryl halides with 1,4-benzenediboronic acid
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Abstract Two 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (Sphos) adducts of cyclopalladated arylpyrazine complexes have been synthesized and characterized. Additionally, the structures of both complexes were determined by single-crystal X-ray analysis
- Xiao, Zhi-Qiang,Xu, Chen,Li, Hong-Mei,Han, Xin,Wang, Zhi-Qiang,Fu, Wei-Jun,Hao, Xin-Qi,Song, Mao-Ping
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p. 501 - 508
(2015/07/28)
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- TETRACATIONIC CYCLOPHANES AND THEIR USE IN THE SEQUESTRATION OF POLYAROMATIC HYDROCARBONS BY WAY OF COMPLEXATION
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Novel tetracationic cyclophanes incorporating π-electron poor organic compounds into their ring structures, as well as methods of making the cyclophanes, are provided. The cyclophanes are able to form electron donor-acceptor complexes with a variety of polyaromatic hydrocarbons (PAHs) ranging in size, shape, and electron density. Also provided are methods of using the cyclophanes in the sequestration of PAHs in liquid or gaseous samples, the separation of PAHs from liquid or gaseous samples, the detection of PAHs in liquid samples, and the exfoliation of graphene via pseudopolyrotaxane formation.
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Paragraph 0072
(2014/07/08)
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- Screening Hofmann compounds as CO2 sorbents: Nontraditional synthetic route to over 40 different pore-functionalized and flexible pillared cyanonickelates
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A simple reaction scheme based on the heterogeneous intercalation of pillaring ligands (HIPLs) provides a convenient method for systematically tuning pore size, pore functionality, and network flexibility in an extended series of pillared cyanonickelates (PICNICs), commonly referred to as Hofmann compounds. The versatility of the approach is demonstrated through the preparation of over 40 different PICNICs containing pillar ligands ranging from ～4 to ～15 A in length and modified with a wide range of functional groups, including fluoro, aldehyde, alkylamine, alkyl, aryl, trifluoromethyl, ester, nitro, ether, and nonmetalated 4,4′-bipyrimidine. The HIPL method involves reaction of a suspension of preformed polymeric sheets of powdered anhydrous nickel cyanide with an appropriate pillar ligand in refluxing organic solvent, resulting in the conversion of the planar [Ni2(CN)4] n networks into polycrystalline three-dimensional porous frameworks containing the organic pillar ligand. Preliminary investigations indicate that the HIPL reaction is also amenable to forming Co(L)Ni(CN)4, Fe(L)Ni(CN)4, and Fe(L)Pd(CN)4 networks. The materials show variable adsorption behavior for CO2 depending on the pillar length and pillar functionalization. Several compounds show structurally flexible behavior during the adsorption and desorption of CO2. Interestingly, the newly discovered flexible compounds include two flexible Fe(L)Ni(CN)4 derivatives that are structurally related to previously reported porous spin-crossover compounds. The preparations of 20 pillar ligands based on ring-functionalized 4,4′-dipyridyls, 1,4-bis(4-pyridyl)benzenes, and N-(4-pyridyl)isonicotinamides are also described.
- Culp, Jeffrey T.,Madden, Catherine,Kauffman, Kristi,Shi, Fan,Matranga, Christopher
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supporting information
p. 4205 - 4216
(2013/05/22)
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- Novel anthracene-based cylindrical macrotricyclic polyether: Powerful host for bispyridinium dications
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A novel anthracene-based cylindrical macrotricyclic polyether containing two dibenzo-30-crown-10 cavities has been synthesized and shown to be a powerful host to form 1:1 stable complexes with the rodlike bispyridinium dications (Ka > 105 M-1). Moreover, it was found that the complexes could all self-assemble into linear supramolecular arrays and further 2D mosaic-like architectures in the solid state.
- Su, Yong-Sheng,Chen, Chuan-Feng
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supporting information; experimental part
p. 1888 - 1891
(2010/09/16)
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- Metal-Metal Interactions Across Symmetrical Bipyridyl Bridging Ligands in Binuclear Seventeen-electron Molybdenum Complexes
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A series of 17-electron mononuclear complexes and their binuclear counterparts 2(μ-X)> benzene (bpeb) or 1,4-bis(4-pyridyl)benzene (bpb)> have been prepared.Electrochemical studies show that the reduction potentials of the mononuclear complexes are sensitive to the degree of unsaturation in the monodentate ligand X, whereas the oxidation potentials are virtually constant.This suggests that the redox orbital involved in the reductions have considerable ligand-based character whereas the oxidations are more strongly metal-centred.This is supported by the electrochemical properties of the binuclear complexes, where the oxidation potentials are in every case coincident but the splitting between the reduction potentials of the equivalent molybdenum centres varies from 0.16 V (X = bpeb) to 0.56 V (X = bpac).By contrast the splitting of the redox potentials of pentaammineruthenium(II) fragments at either end of 'extended' 4,4'-bipyridine analogues of this type is an order of magnitude smaller.This strong interaction between moieties is in part due to a planar conformation of the bridging ligands, even when they are in principle capable of free rotation, since changing the bridging ligand from 4,4'-bipyridine to 3,3'-dmbipy (which cannot be planar due to the steric effects of the methyl groups) results in a decrease in the splitting of the reduction potentials from 0.77 to 0.38 V.The EPR spectra of the binuclear complexes all show that the two unpaired electrons (one at each 17-electron molybdenum centre) are in fast exchange across the bridging ligand at room temperature.
- Das, Amitava,Maher, John P.,McCleverty, Jon A.,Badiola, Jon A. Navas,Ward, Michael D.
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p. 681 - 686
(2007/10/02)
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- Synthesis and Characterization of New Conjugation-extended Viologens Involving a Central Aromatic Linking Group
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New viologens, in which two pyridinium moieties are linked by a central five-membered heteroaromatic or phenylene framework, giving stable radical cations on single electron reduction and showing an intense fluorescence emission are efficiently synthesize
- Takahashi, Kazuko,Nihira, Takayasu,Akiyama, Kimio,Ikegami, Yusaku,Fukuyo, Emiko
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p. 620 - 622
(2007/10/02)
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