Design, synthesis and herbicidal activities of novel self-dispreading phenoxy carboxylic acid derivatives for the control of water hyacinth floating on the water surface

Article abstract of DOI:10.1016/j.cclet.2015.04.008

Abstract A series of novel self-dispreading phenoxy carboxylic acid derivatives were designed and synthesized by I₂ catalyzed one-step reaction. Their structures were confirmed by IR, NMR, and HRMS. The derivatives can self-spread and float on the water surface. Preliminary bioassays showed that some compounds, 3i-3p, had excellent herbicidal activities against water hyacinth. This strategy provided a novel approach for the water hyacinth control.

Full text of DOI:10.1016/j.cclet.2015.04.008

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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 462–464
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Short Communication
The distribution of isotopomers in crystals
⇑
Stewart F. Parker
ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
How to calculate the number of
isotopomers and their relative
abundance is defined.
ꢀ
ꢀ
Worked examples of a dihydrate and
borazine are shown.
Methods to ensure that the
calculations are done correctly are
given.
a r t i c l e i n f o
a b s t r a c t
Article history:
Isotopic substitution is used extensively in the physical sciences and particularly in vibrational
spectroscopy. To be able to correctly analyze solid state spectra of crystalline materials, it is essential
to know the isotopic distribution present. Here, I show how the distribution of isotopomers in a crystal
may be calculated for arbitrary numbers of isotopes and sites.
Received 20 January 2014
Received in revised form 5 January 2015
Accepted 11 January 2015
Available online 17 January 2015
Ó 2015 Elsevier B.V. All rights reserved.
Keywords:
Isotope
Isotopomer
Isotopic substitution
Multinomial theorem
Borazine
Hydrate
Isotopic substitution is used extensively in the physical sci-
ences. It finds application in biochemistry e.g. as a tracer in studies
of metabolism [1], in neutron scattering where the different scat-
tering lengths of hydrogen and deuterium provide contrast in
small angle neutron scattering, neutron reflectometry and total
scattering studies [2]. Chemistry is the area where it is probably
most exploited; it is used to distinguish otherwise identical species
to aid mechanistic studies but spectroscopy is the area where it is
indispensable. Nuclear magnetic resonance (NMR) and Mössbauer
spectroscopy are techniques that are both element and isotope
specific and isotopic enrichment is often used to improve
sensitivity e.g. 18O NMR and 57Fe Mössbauer. Microwave rotational
spectroscopy makes use of isotopomers of the molecule of interest
to improve the derived structure. The many forms of vibrational
spectroscopy use isotopic substitution to aid assignment and to
provide insight into coupling within and between molecules [3,4].
While many elements are monoisotopic e.g. F, Na, Al, P or effec-
tively so: 1H 99.985%, 14N 99.635%, 16O 99.75%, there are several
common elements that have significant quantities of a second iso-
tope. These include: lithium (6Li 7.5% and 7Li 92.5%), boron (10
19.4% and 11B 80.2%), carbon (12C 98.89% and 13C 1.11%), chlorine
35Cl 75.77% and 37Cl 24.23%) and bromine (79Br 50.49% and 81Br
B
(
49.31%) [5]. In these cases in order to be able to analyze the spectra
it is usually necessary to know how the isotopes are distributed
within the molecules and this is particularly the case for
⇑
Tel.: +44 1235 446182.
E-mail address: stewart.parker@stfc.ac.uk
http://dx.doi.org/10.1016/j.saa.2015.01.013
1386-1425/Ó 2015 Elsevier B.V. All rights reserved.

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S.F. Parker / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 462–464
463
Table 2
vibrational spectra. The same consideration arises when a mole-
cule is isotopically enriched.
Distribution of isotopomers of borazine in natural abundance in the primitive
cell containing four molecules. (a = 10B10B10B = 0.008, b = 10B10B11B = 0.096,
c = 10B11B11B = 0.384 and d = 11B11B11B = 0.512).
This is trivial when there is a single site, the ratio of isotopomers
is simply the natural abundance. Thus 13CO2 is present to the
extent of 1.11% that of 12CO2. In the case of two isotopes, (with
abundances a and b), and two sites the ratio is given by:
Coefficient
Powers
Crystal composition (%)
1
1
1
1
4
4
4
4
4
4
6
6
6
6
6
6
12
12
12
12
12
12
12
12
12
12
12
12
4
4
4
4
4
4
24
a4
0.00
0.01
2.17
6.87
0.00
0.00
0.00
0.14
0.18
11.60
0.00
0.01
0.01
0.82
1.45
23.19
0.00
0.00
0.02
2.17
0.03
0.05
0.72
8.70
0.14
0.24
0.97
11.60
0.00
0.18
0.43
2.17
5.15
20.62
0.36
b4
c4
2
ða þ bÞ ¼ a2 þ 2ab þ b2
ð1Þ
d4
a3b
Thus for a 1:1 mixture of H2O and D2O, a = b = 0.5 and there will
be 25% H2O, 50% HOD and 25% D2O. More generally, where there
are two isotopes and n sites the distribution is given by the
binomial theorem [6]:
a3c
a3d
b3c
b3d
ꢀ
ꢁ
c3d
n
X
n
k
a2b2
a2c2
a2d2
b2c2
b2d2
c2d2
a2bc
a2bd
a2cd
b2cd
ab2c
ab2d
ac2d
bc2d
abc2
abd2
acd2
bcd2
ab2
n
ða þ bÞ ¼
akbnꢁk
ð2Þ
k¼0
where the binomial coefficient is defined as:
ꢀ
ꢁ
n
k
n!
¼
ð3Þ
k!ðn ꢁ kÞ!
(The coefficients in the expansion are also given by the (n + 1)
row of Pascal’s triangle). Thus for benzene with n = 6, the
expansion is:
a6 þ 6a5b þ 15a4b2 þ 20a3b3 þ 15a2b4 þ 6ab5 þ b6
ð4Þ
For natural abundance carbon, a = 0.989, b = 0.011 and the iso-
topic distribution is: 12C6H6 93.58%, 12C513CH6 6.24%, 12C413C2H6
0.17% with 12C133C3H6, 12C123C4H6, 12C13C5H6 and 13C6H6 all
<3 ꢂ 10ꢁ3%.
ac2
ad2
Where it is only necessary to consider the isotopic distribution
within a single molecule, the analysis is straightforward. The prob-
lem becomes more complex when it is necessary to consider more
than two isotopes or more than one molecule. The latter situation
will arise whenever there is more than one of the molecule of
interest in the primitive cell of a crystalline solid. In this case it
is necessary to consider the distribution of isotopomers within
the material. This may be calculated using the multinomial
theorem [7]:
bc2
bd2
cd2
abcd
R
= 256
Count = 35
R = 100.00
this class. There is one formula unit in the primitive cell [8], thus
there are two water molecules present. If the material is synthes-
ised from an aqueous solution with the distribution a H2O, b
HOD and c D2O, where a + b + c = 1, then from Eqs. (5) and (7):
ꢀ
ꢁ
n
X
n
n
kb
k
x
a
ðaþbþc þ...þ
x
Þ ¼
ak ckc ...
b x
ka;kb;kc;...kx
kaþk þkcþ...þk ¼n
x
b
2
ða þ b þ cÞ ¼ a2 þ b2 þ c2 þ 2ab þ 2ac þ 2bc
ð8Þ
ð5Þ
Table 1 gives the distribution for various isotopic ratios. It is
often desirable to generate HOD in either a largely H2O or D2O
environment so as to decouple the O–D (or O–H) vibration. It can
be seen that to achieve this goal, a large H2O:D2O ratio (or vice
versa) is the best choice.
A more complex example is when an element has two isotopes
with significant abundances. This commonly occurs in boron
chemistry because of the ꢄ1:4 ratio of 10B:11B. Consider borazine
(1,3,5,2,4,6-triazatriborinane, B3N3H6), an inorganic analog of ben-
zene. Assuming natural abundance, gas phase borazine will have a
composition given by Eqs. (2) and (3) with n = 3, since there are
three possible positions for the boron atoms. The resulting
where the ki are integers such that:
ka þ kb þ kc þ ꢃ ꢃ ꢃ þ kx ¼ n
ð6Þ
ð7Þ
and the multinomial coefficient is given by:
ꢀ
ꢁ
ꢀ
ꢁ
n
n!
¼
ka!kb!kc! . . . kx!
ka; kb; kc; . . . kx
To illustrate the use of Eqs. (5)–(7), consider the case where the
aim is to investigate the hydrogen bonding in a hydrate. Materials
with more than one water molecule present commonly occur in
mineralogy and gypsum, CaSO4ꢃ2H2O is an important example of
Table 1
Distribution of isotopomers of water in a crystal with a primitive cell containing two water molecules.
H2O:D2O
Molecular composition (%)
Crystal composition (%)
H2O
HOD
D2O
1.00
6.25
25.00
44.45
64.00
H2O + H2O
HOD + HOD
D2O + D2O
H2O + HOD
H2O + D2O
D2O + HOD
9:1
3:1
1:1
1:2
1:4
81.00
56.25
25.00
11.11
4.00
9.00
37.50
50.00
44.44
32.00
65.61
31.64
6.25
1.23
0.16
3.24
14.06
25.00
19.76
10.24
0.01
0.39
6.25
19.76
40.96
29.16
42.19
25.00
9.87
1.62
7.03
12.50
9.87
0.36
4.69
25.00
39.52
40.96
2.56
5.12

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464
S.F. Parker / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 140 (2015) 462–464
composition is: 0.8% 10B10B10B, 9.6% 10B10B11B, 38.4% 10B11B11B and
51.2% 11B11B11B. For solid borazine with four molecules in the
primitive cell [9], the distribution is given by:
Consideration of Table 2 shows some surprises. As an initial
guess, since 11B is present to the extent of 80%, it might be
expected that the crystal would be dominated by the all-11B spe-
cies. This is clearly not the case and it is only a minor constituent
(d4 = 6.87%). The largest constituents are: c2d2 = (10B11B11B,
10B11B11B, 11B11B11B, 11B11B11B) = 23.19% and cd3 = (10B11B11B,
11B11B11B, 11B11B11B, 11B11B11B) = 20.62%.
4
ða þ b þ c þ dÞ
ð9Þ
The expansion of Eq. (9) is given in Table 2. There are four useful
checks that can be applied to ensure that all of the terms have been
included: Check 1: from Eq. (6), it follows that the sum of the pow-
ers must be 4 for all terms (i.e. n in the general case). Check 2: the
total number of terms is given by the sum of the coefficients and in
general is given by mn where m is the number of isotopomers. In
this instance m = 4 and n = 4, hence there are 44 = 256 terms in
agreement with the last entry in column 1 of Table 2. Check 3:
the number of terms involving a, b, c and d is given by [7]:
The methods illustrated here are completely general and allow
the isotopic distribution of a molecule or a crystal to be calculated.
References
[1] S.E. McQuaid, L. Hodson, M.J. Neville, A.L. Dennis, J. Cheeseman, S.M.
Humphreys, T. Ruge, M. Gilbert, B.A. Fielding, K.N. Frayn, F. Karpe, Diabetes
60 (2011) 47–55.
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[3] S. Pinchas, I. Laulicht, Infrared Spectra of Labelled Compounds, Academic Press,
London, UK, 1971.
[4] J.R. Durig, Utility of isotopic data, in: J.M. Chalmers, P.R. Griffiths (Eds.),
ꢀ
ꢁ
n þ m ꢁ 1
ð10Þ
n
Handbook of Vibrational Spectroscopy, vol. 3, John Wiley
Chichester, UK, 2002, pp. 1935–1947.
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Interscience, New York, USA, 1993, pp. 106–107.
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where the coefficient is defined in Eq. (3). For the present case,
n + m ꢁ 1 = 7, n = 4 hence 7!/(4!(7–4)!) = 35, in agreement with
the last entry in column 2 of Table 2. Check 4: Eq. (5)is an equation,
thus both sides must sum to the same value. For the special case
where the sum of the isotopic abundances is unity, since 1n = 1,
the sum of the individual compositions must also be unity (i.e.
100%), as seen in the last entry of column 3 of Table 2. In the case
where a + b + c + . . . – 1 (e.g. if an isotope or isotopomer with low
abundance is omitted) then the sum will differ from unity.
[8] P.F. Schofield, C.C. Wilson, K.S. Knight, I.C. Stretton, Z. Kristallogr. 215 (2000)
707–710.
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