Chemistry of the Heterotriquinanes and Heterotriquinacenes

Synlett ◽  
2021 ◽  
Author(s):  
Mark Mascal ◽  
Nema Hafezi
Keyword(s):  
Symmetry Axis ◽  
World Record ◽  
Bond Lengths ◽  
Sn2 Reaction ◽  
Tertiary Center ◽  
The Future

AbstractTriquinanes are tricyclic hydrocarbons that have fused cyclopentane rings. Although there are linear and angular triquinanes that are doubly fused, this Account focuses exclusively on the ‘triquinacane’, or triply fused structure with a heteroatom (nitrogen or oxygen) on the C 3v symmetry axis. Azatriquinane- and oxatriquinane-based species tend to show remarkable and often unexpected chemistry, and have variously comprised the most basic trialkyl amine, a superbasic proton chelate, trigonal pyramidal ligand platforms, novel calixiform hosts, aromatic hemispheres of hetero-C20 fullerenes, cocrystallizing agents for eliminating rotational disorder in fullerene crystals, the first water-stable, chromatographable trialkyloxonium species, the first isolable allylic oxonium species, world-record C–O bond lengths, rapid SN2 reaction at a tertiary center, and R4O2+ (oxadionium) species.1 Introduction2 Azatriquinane3 Azatriquinacene4 Aromatic Azatriquinacene-Based Systems5 Oxatriquinane6 Tetravalent Oxygen7 Oxatriquinacene8 The Future

STEREOCHEMSTRY OF ARSENIC: PART III. o-PHENYLENEDIARSINE OXYCHLORIDE

1962 ◽  
Vol 40 (6) ◽  
pp. 1113-1117 ◽  
Author(s):  
W. R. Cullen ◽  
J. Trotter
Keyword(s):  
Symmetry Axis ◽  
Van Der Waals ◽  
Membered Ring ◽  
Unit Cell ◽  
The Other ◽  
Van Der Waals Interactions ◽  
Chlorine Atoms ◽  
Space Group ◽  
Bond Lengths ◽  
Aromatic Character

Crystals of o-phenylenediarsine oxychloride, C6H4As2Cl2O, are monoclinic with four molecules in a unit cell of dimensions a = 14.50, b = 8.38, c = 7.66 Å, β = 105.8°, space group C2/c. The structure has been determined from projections along the b and c axes. Each molecule is situated on a 2-fold symmetry axis and is planar except for the chlorine atoms, which lie one on either side of the plane of the other atoms. The values of the bond lengths and valency angles have been obtained. Abnormal valency angles at the arsenic and oxygen atoms are the result of their presence in the five-membered ring, and the unusual stability of the molecule in spite of these angles can be interpreted in terms of aromatic character, involving dπ–pπ bonding. The intermolecular separations correspond to normal van der Waals interactions.

scholarly journals Zen and the Art of Academic Maintenance

2016 ◽  
Author(s):  
Stephen Curry
Keyword(s):  
Research Paper ◽  
New Work ◽  
World Record ◽  
Living Thing ◽  
The World ◽  
The Future ◽  
The Moment ◽  
Future Consequences

Watch the VIDEO of the presentation.Robert Pirsig’s book, Zen and the Art of Motorcycle Maintenance, which is an exploration of the metaphysics of quality, is a Guinness world record holder. No best-seller has been rejected by more publishers – 121 in all. That numerical anomaly, mentioned at the top of the Wikipedia entry for the book (because of our obsession with quantity and rank), reminds us that identifying quality is hard. It requires expertise, but also the imagination to anticipate the future consequences of any new work – whether it be a book or a research paper. Time and again in academia, we get such judgments wrong. And yet, our systems of incentive and reward are increasingly tightly geared to the moment and place of publication. The evaluation of the work itself, or of the idea that it is a living thing that reaches out into the world, is being undermined as busy researchers strive to please busy masters who turn too often to numbers to make their assessment. Quantity is the pernicious proxy that trumps quality. But we must rediscover quality, in all its dimensions, if we are to maintain the reputation of the academy for unflinching interrogation. And one of the most important of those dimensions is openness, which can serve not only as a buttress for quality, but also as a reminder to the academy that freedom of inquiry brings responsibilities to society that can also be enriching.

The pitch of the world: cricket and Chris Searle

Race & Class ◽  
2009 ◽  
Vol 51 (2) ◽  
pp. 44-58 ◽  
Author(s):  
Claire Westall ◽  
Neil Lazarus
Keyword(s):  
Inner City ◽  
Social Relations ◽  
World Record ◽  
The World ◽  
Personal Contribution ◽  
The Future ◽  
Fast Bowler ◽  
The Subject ◽  
A Site ◽  
The Relationship

Part of Chris Searle’s wide-ranging contribution to Race & Class — and the subject of this article — is a body of cricket writing that exposes the crippling imperial legacies of the game but still insists on its potential for the future, particularly in England; a future Searle understands as emerging from the country’s working-class, multi-ethnic, inner-city communities. Searle is indebted to C. L. R. James’s Beyond a Boundary (1963) and, like James, sees cricket as a site for the expression, playing out and (sometimes) the imaginary resolution of social relations. Searle also follows James in arguing that, because of the game’s sociality, the politics of cricketing performance must be assessed in terms of the relationship between players and their communities. In this context, he has analysed the significance of figures like Devon Malcolm, England’s Jamaican-born fast bowler, and Brian Lara, the world-record holding West Indies batsman. Notably, Searle’s academic and personal contribution has been ‘Towards a cricket of the future’, as one of his own pieces is entitled. He has also helped lay the ground for a critique of the globalised televisual spectacle that is, increasingly, the international game of cricket.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Status of the Lick Proper Motion Program

1978 ◽  
Vol 48 ◽  
pp. 387-388
Author(s):  
A. R. Klemola
Keyword(s):  
Proper Motion ◽  
The Future

Second-epoch photographs have now been obtained for nearly 850 of the 1246 fields of the proper motion program with centers at declination -20° and northwards. For the sky at 0° and northward only 130 fields remain to be taken in the next year or two. The 270 southern fields with centers at -5° to -20° remain for the future.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

Freeze-fracture cytochemistry: A goal set by Russell Steere in 1957

1993 ◽  
Vol 51 ◽  
pp. 60-61
Author(s):  
Nicholas J Severs
Keyword(s):  
Chemical Nature ◽  
Biological Systems ◽  
Freeze Fracture ◽  
Structural Components ◽  
Major Goal ◽  
Membrane Biology ◽  
Routine Application ◽  
The Future ◽  
Freeze Etching

In his pioneering demonstration of the potential of freeze-etching in biological systems, Russell Steere assessed the future promise and limitations of the technique with remarkable foresight. Item 2 in his list of inherent difficulties as they then stood stated “The chemical nature of the objects seen in the replica cannot be determined”. This defined a major goal for practitioners of freeze-fracture which, for more than a decade, seemed unattainable. It was not until the introduction of the label-fracture-etch technique in the early 1970s that the mould was broken, and not until the following decade that the full scope of modern freeze-fracture cytochemistry took shape. The culmination of these developments in the 1990s now equips the researcher with a set of effective techniques for routine application in cell and membrane biology.Freeze-fracture cytochemical techniques are all designed to provide information on the chemical nature of structural components revealed by freeze-fracture, but differ in how this is achieved, in precisely what type of information is obtained, and in which types of specimen can be studied.

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