A generic one-pot hydrothermal synthesis route has been successfully designed and utilized to in situ grow uniform manganese oxide nanorods and nanowires onto the cordierite honeycomb monolithic substrates, forming a series of nanoarray-based monolithic catalysts. During the synthesis process, three types of potassium salt oxidants have been used with different reduction potentials, i.e., K2Cr2O7, KClO3, and K2S2O8, denoted as HM-DCM, HM-PCR, and HM-PSF, respectively. The different reduction potentials of the manganese source (Mn(2+)) and oxidants induced the formation of manganese oxide nanoarrays with different morphology, surface area, and reactivity of carbon monoxide (CO) oxidation. K2Cr2O7 and KClO3 can induce sharp and long nanowires with slow growth rates due to their low reduction potentials. In comparison, the nanoarrays of HM-PSF presented shorter nanorods but displayed an efficient 90% CO oxidation conversion at 200 °C (T90) without noble-metal loading. Reducibility tests for the three monolithic catalysts by hydrogen temperature-programmed reduction revealed an activation energy order of HM-PSF > HM-DCM > HM-PCR for CO oxidation. The characterizations of oxygen temperature-programmed desorption and X-ray photoelectron spectroscopy indicated the abundant surface-adsorbed oxygen and lattice oxygen contributing to the superior reactivity of HM-PSF. The straightforward synthetic process showed a scalable, low-cost, and template-free method to fabricate manganese oxide nanoarray monolithic catalysts for exhaust treatment.

Fused pyrimidine derivativesFused pyrimidine derivatives R 0515 Simple One-Pot Three-Component Synthesis of 2-Oxo-1,11b-dihydro-2H-pyrimido[2,1-a]isoquinolines. -(ADIB*, M.; MOLLAHOSSEINI, M.; YAVARI, H.; SAYAHI, M. H.; BIJANZADEH, H. R.; Synthesis 2004, 6, 861-864; Dep. Chem., Fac. Sci., Tehran Univ., Tehran, Iran; Eng.) -C. Herrmann

No abstract

One of the greatest challenges with single-walled carbon nanotube (SWNT) photovoltaics and nanostructured devices is maintaining the nanotubes in their pristine state (i.e., devoid of aggregation and inhomogeneous doping) so that their unique spectroscopic and transport characteristics are preserved. To this effect, we report on the synthesis and self-assembly of a C60-functionalized flavin (FC60), composed of PCBM and isoalloxazine moieties attached on either ends of a linear, C-12 aliphatic spacer. Small amounts of FC60 (up to 3 molar %) were shown to coassembly with an organic soluble derivative of flavin (FC12) around SWNTs and impart effective dispersion and individualization. A key annealing step was necessary to perfect the isoalloxazine helix and expel the C60 moiety away from the nanotubes. Steady-state and transient absorption spectroscopy illustrate that 1% or higher incorporation of FC60 allows for an effective photoinduced charge transfer quenching of the encased SWNTs through the seamless helical encase. This is enabled via the direct π-π overlap between the graphene sidewalls, isoalloxazine helix, and the C60 cage that facilitates SWNT exciton dissociation and electron transfer to the PCBM moiety. Atomistic molecular simulations indicate that the stability of the complex originates from enhanced van der Waals interactions of the flexible spacer wrapped around the fullerene that brings the C60 in π-π overlap with the isoalloxazine helix. The remarkable spectral purity (in terms of narrow E(S)ii line widths) for the resulting ground-state complex signals a new class of highly organized supramolecular nanotube architecture with profound importance for advanced nanostructured devices.

O n e -P o t S y n t h e s i s o f 2 -O x o -1 , 1 1 b -d i h y d r o -2 H -p y r i m i d o [ 2 , 1 -a ] i s o q u i n o l i n e sAbstract: Isoquinoline reacts smoothly with dialkyl acetylenedicarboxylates in the presence of isocyanates to produce dialkyl 2-oxo-1,11b-dihydro-2H-pyrimido[2,1-a]isoquinoline-3,4-dicarboxylates in good yields.The development of simple synthetic routes for widely used organic compounds from readily available reagents is one of the major tasks in organic synthesis. 1 Bridgehead nitrogen heterocycles are of interest because they constitute an important class of natural and unnatural products, many of which exhibit useful biological activity. 2,3 The interest in fused bicyclic 6-6 systems with one ring junction and one extra nitrogen atom, stems from the appearance of saturated and partially saturated pyrido[1,2-a]pyrimidine ring systems and their 8,9-benzo analogues (pyrimido[2,1-a]isoquinolines) in many biologically active compounds and natural products, 3-10 some of which are key intermediates for the synthesis of rutaecarpine alkaloids, some have characteristic pharmacological properties such as analgesic, antiallergic, antiasthmatic, and antipsychotic agents, and some are neutral hydrogen chloride acceptors in organic synthesis. 3 As part of our current studies on the development of new routes in heterocyclic synthesis, 11 in this paper, we wish to report a simple synthesis of functionalized pyrimido[2,1-a]isoquinolines.The reaction of isoquinoline (1) and dialkyl acetylenedicarboxylates (2) in the presence of isocyanates (3) proceeds smoothly in dichloromethane at ambient temperature to produce dialkyl 2-oxo-1,11b-dihydro-2H-pyrimido[2,1-a]isoquinoline-3,4-dicarboxylates (4) in 75-99% yields (Scheme 1).The reactions were carried out by first mixing isoquinoline and the isocyanate and then the acetylenic ester was added slowly, proceeding spontaneously in CH 2 Cl 2 , and were complete within an hour (see experimental).The structures of compounds 4a-g were deduced from their elemental analyses and their IR, 1 H NMR and 13 C NMR spectra. The mass spectrum of 4a displayed the molecular ion (M + ) peak at m/z = 390, which is consistent with the 1:1:1 adduct of isoquinoline, dimethyl acetylenedicarboxylate (DMAD) and phenyl isocyanate. The 1 H NMR spectrum of 4a exhibited three singlets readily recognized as arising from two methoxy (d = 3.87 and 3.98) and the methine (d = 6.55) protons, an AB quartet system for two vinylic protons of the enamine moiety of isoquinoline ring (d = 6.01 and 6.56, J = 7.8 Hz), and the characteristic multiplets for the aromatic protons (d = 6.6-7.2). Scheme 1Downloaded by: University of British Columbia. Copyrighted material.