From owner-chemistry@ccl.net Tue May 28 03:24:00 2013
From: "Michel Petitjean petitjean.chiral/./gmail.com" <owner-chemistry-#-server.ccl.net>
To: CCL
Subject: CCL: How to characterize and change the tacticity of polymer chain
Message-Id: <-48742-130528032214-4664-Xiri0SwgHEcuDv0LyT3mPA-#-server.ccl.net>
X-Original-From: Michel Petitjean <petitjean.chiral:gmail.com>
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Date: Tue, 28 May 2013 09:22:03 +0200
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Sent to CCL by: Michel Petitjean [petitjean.chiral*o*gmail.com]
Dear Chaofu,

Having the asymmetric carbon at the origin and having fixed the
smaller substituent 1, you need to know the sense of "rotation" of 2,3,4.
The vector product 2*3 is a direct vector (non unit) to the oriented plane
defined by the vectors 2 and 3 taken in this order. If this vector product
has an acute angle with 4, the dot product 4.(2*3)=(2*3).4 is
positive, and if it
has an obtuse angle with 4, the dot product 4.(2*3)=(2.3).4 is negative.
This dot product is exactly the determinant [4,2,3]=[2,3,4] (can be
checked by hand).
Remark, unless you have a chemically impossible geometry,
the vector 1 is necessarily placed where desired,
so that the whole computation relies on 2,3,4.

Best,
Michel.

2013/5/28 WuChaofu xiaowu759,,hotmail.com <owner-chemistry(a)ccl.net>:
>
> Sent to CCL by: WuChaofu [xiaowu759[a]hotmail.com]
> Dear Michel,
> Thank you very much! You surely give such a good suggestion. However, I can not quite understand why the tacticity of polymer chains can be determined by computing the sign of determinant [2,3,4]. Could you explain it further, please?
> Yours sincerely,
> Chaofu Wu
>> ----------------------------------------
>>> Date: Mon, 27 May 2013 18:04:34 +0200
>>> Subject: Re: CCL: How to characterize and change the tacticity of polymer chain
>>> From: petitjean.chiral(a)gmail.com
>>> To: xiaowu759(a)hotmail.com
>>>
>>> Carbon is the asymmetric carbon, assumed to have coordinates (x,y,z)=(0,0,0).
>>> Best regards,
>>> Michel.
>>>