711-02-4Relevant articles and documents
A Practical and Cost-Effective Method for the Synthesis of Bicyclo[22.2]octane-1,4-dicarboxylic Acid
Le Marquer, Nicolas,Laurent, Mathieu Yves,Martel, Arnaud
, p. 2185 - 2187 (2015)
A short and efficient synthesis of bicyclo[2.2.2]octane-1,4-dicarboxylic acid involving the formation of a semicarbazone is developed, and a reproducible protocol for the reduction of this semicarbazone is described. The use of microwaves significantly shortens the duration of the sequence to the diacid compared to the previously described synthetic method. In addition, by shifting from the use of large amounts of Raney nickel to a solid-phase process, both the safety and cost are improved notably.
Tuning Singlet Fission in π-Bridge-π Chromophores
Kumarasamy, Elango,Sanders, Samuel N.,Tayebjee, Murad J. Y.,Asadpoordarvish, Amir,Hele, Timothy J. H.,Fuemmeler, Eric G.,Pun, Andrew B.,Yablon, Lauren M.,Low, Jonathan Z.,Paley, Daniel W.,Dean, Jacob C.,Choi, Bonnie,Scholes, Gregory D.,Steigerwald, Michael L.,Ananth, Nandini,McCamey, Dane R.,Sfeir, Matthew Y.,Campos, Luis M.
, p. 12488 - 12494 (2017/09/23)
We have designed a series of pentacene dimers separated by homoconjugated or nonconjugated bridges that exhibit fast and efficient intramolecular singlet exciton fission (iSF). These materials are distinctive among reported iSF compounds because they exist in the unexplored regime of close spatial proximity but weak electronic coupling between the singlet exciton and triplet pair states. Using transient absorption spectroscopy to investigate photophysics in these molecules, we find that homoconjugated dimers display desirable excited-state dynamics, with significantly reduced recombination rates as compared to conjugated dimers with similar singlet fission rates. In addition, unlike conjugated dimers, the time constants for singlet fission are relatively insensitive to the interplanar angle between chromophores, since rotation about σ bonds negligibly affects the orbital overlap within the π-bonding network. In the nonconjugated dimer, where the iSF occurs with a time constant >10 ns, comparable to the fluorescence lifetime, we used electron spin resonance spectroscopy to unequivocally establish the formation of triplet-triplet multiexcitons and uncoupled triplet excitons through singlet fission. Together, these studies enable us to articulate the role of the conjugation motif in iSF.
New ultrahigh affinity host-guest complexes of cucurbit[7]uril with bicyclo[2.2.2]octane and adamantane guests: Thermodynamic analysis and evaluation of M2 affinity calculations
Moghaddam, Sarvin,Yang, Cheng,Rekharsky, Mikhail,Ko, Young Ho,Kim, Kimoon,Inoue, Yoshihisa,Gilson, Michael K.
, p. 3570 - 3581 (2011/05/04)
A dicationic ferrocene derivative has previously been shown to bind cucurbit[7]uril (CB[7]) in water with ultrahigh affinity (ΔGo= -21 kcal/mol). Here, we describe new compounds that bind aqueous CB[7] equally well, validating our prior suggestion that they, too, would be ultrahigh affinity CB[7] guests. The present guests, which are based upon either a bicyclo[2.2.2]octane or adamantane core, have no metal atoms, so these results also confirm that the remarkably high affinities of the ferrocene-based guest need not be attributed to metal-specific interactions. Because we used the M2 method to compute the affinities of several of the new host-guest systems prior to synthesizing them, the present results also provide for the first blinded evaluation of this computational method. The blinded calculations agree reasonably well with experiment and successfully reproduce the observation that the new adamantane-based guests achieve extremely high affinities, despite the fact that they position a cationic substituent at only one electronegative portal of the CB[7] host. However, there are also significant deviations from experiment, and these lead to the correction of a procedural error and an instructive evaluation of the sensitivity of the calculations to physically reasonable variations in molecular energy parameters. The new experimental and computational results presented here bear on the physical mechanisms of molecular recognition, the accuracy of the M2 method, and the usefulness of host-guest systems as test-beds for computational methods.
