P. Anandan et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 121 (2014) 508–513
509
various industrial applications of single crystals. Since the semior-
ganic single crystals possess the attractive properties of both or-
ganic and inorganic crystal, Scientists and Researchers focused
their interest in growing as many semiorganic single crystals
[1,2]. Amino acids are identified as potential candidates for the
growth of single crystals with some inorganic acids which exhibits
the most essential nonlinear optical (NLO) property for frequency
conversion applications [3–5]. In recent decade the derivatives of
amino acids like alanine, valine, lucene etc., are identified as poten-
tial candidates for the NLO device fabrication [6–9].
The dimensions of the crystals have been measured by the dig-
ital Vernier caliper and the average rates of growth along the crys-
tallographic directions (a, b, c) have been compared. In the case of
L-histidine crystal, the growth rate along ‘c’ direction is found to be
much greater than that of other two directions. On the other hand,
the growth rate along ‘a’ and ‘c’ directions of LHHC crystal has been
observed to be much greater than that along ‘b’ direction. Among
these two directions, the growth rate along ‘c’ direction is slightly
greater than that along ‘a’ direction. When comparing the two
crystals, the growth rate of LHHC crystal along ‘a’ direction has
been found to be increased and decreased along ‘b’ and ‘c’ direc-
tions as well. The reduction of growth rate along ‘c’ direction and
increased growth rate along ‘a’ direction have made LHHC crystal
as stubbier one. The growth rates along the three crystallographic
directions have been tabulated in Table 1.
L-histidine is one such amino acid which gave a huge number of
derivatives of semiorganic single crystals with NLO property. Re-
cently many authors have grown and investigated the properties
of
dates for NLO applications [10–13]. Investigation on the possibility
of formation of -histidine derivative with various acids have been
reported and also found that the -histidine gave two different
L-histidine derivative crystals and identified as potential candi-
L
L
Characterization techniques
crystal structures with hydrochloric acid as well as hydrobromic
acid when it is mixed in 1:2 M ratios, respectively [14]. The lattice
parameters and crystal structure of L-histidine dihydrochloride
were determined and reported quite long back [15]. Whereas the
bulk growth have been reported recently [16]. But still, there is
lack of literature on the properties of L-histidine dihydrochloride.
The powdered crystal samples and as grown good quality seed
crystals were used to study the properties using various tech-
niques. Single crystal X-ray diffraction analyses were made using
suitable crystal samples to confirm the crystal system and lattice
parameter values by ENRAF CAD – 4 diffractomer with Mo K
a
In order to study the growth aspects and properties of the crystals
grown in the solution of the above said molar ratio, in the present
(k = 0.7107 Å) radiation. Powder X-ray diffraction patterns were re-
corded to study the structural variations of the grown crystal by
using XPERT PRO diffraction system. The powder sample was
mixed with KBr 1:20 weight ratio and made as a pellet to study
the Fourier transform infrared spectral analysis of the grown crys-
tals by using Nicolet iS50 Spectrometer in order to find the pres-
ence of various functional groups. FT-Raman spectral analyses
have also been done using Bruker RFS model spectrometer and
the functional groups were confirmed. Linear optical properties
of the crystals were studied by UV–Vis Spectrophotometer and
nonlinear optical properties were tested by Kurtz Perry powder
technique [17]. Thermal analyses were carried out in the nitrogen
atmosphere from room temperature to 600 °C using an instrument
EXSTAR TG/DTA 6200 model supplied by SII Nanotechnology,
Japan.
study, attempts have been made to grow bulk crystal of
dihydrochloride. But, in contradiction to the expectations two dif-
ferent crystals of -histidine were obtained in the said solution. The
grown crystals were identified as -histidine and -histidine hydro-
chloride monohydrate (LHHC). Characterization on structural, opti-
cal and thermal properties of -histidine has not been reported so
L-histidine
L
L
L
L
far. The growth aspects of the obtained two crystals and their prop-
erties were studied and discussed in this paper.
Experiment
Synthesis and growth aspects
L
-histidine (99% pure) and hydrochloric acid (HCl) (Merk Prod-
uct) were taken in 1:2 M ratios in excess of double distilled milli
pore water as the starting material. The calculated amount of -his-
tidine was mixed in excess of double distilled milli pore water and
the measured amount of HCl was added slowly with stirring to the
Results and discussion
L
Single crystal X-ray diffraction analyses
Single crystal X-ray diffraction analysis has been carried out to
determine the lattice parameters. The data have been collected at
mixture of water and L-histidine. After the solution become homo-
geneous (i.e., after continuous stirring for two hours), the solution
was filtered to avoid the inclusion of impurities during the stirring
and maintained at room temperature (300 K) by using a constant
temperature bath controlled to an accuracy of 0.01 K. The excess
water was allowed to evaporate slowly so as to reach the satura-
tion level of the solution. After the solution has attained the satu-
ration level, well controlled evaporation was maintained to avoid
the spurious nucleation. Though the evaporation was controlled
carefully, single crystals were grown with two different external
morphologies in the same solution. For the first twenty days only
the needle like crystals had grown. After twenty days, the second-
ary nucleation was observed in the same solution and the crystals
grown thereafter were in different morphology (bulk in shape) to
the previous ones. Several attempts were made by adopting the
same procedure and the growth aspects have been confirmed. Seed
and grown crystals were carefully harvested from the solution and
the photographs of as grown crystals are shown in the Fig. 1. The
293 K using Mo K
a (k = 0.71069 Å) radiation. The grown crystals
possess orthorhombic structure and the lattice parameter values
of the grown crystal are tabulated in Table 2. The lattice parame-
ters of the different samples of each category have been measured
and the formation of two different crystals has been confirmed.
The lattice parameters of needle like crystals have very good agree-
ment with the reported lattice parameters of
[18]. On the other hand, the lattice parameters of bulk samples
do not agree with -histidine dihydrochloride [15] but agree with
-histidine hydrochloride monohydrate crystal as well [16,19,20].
Fortunately, there were no reports on the bulk growth and charac-
terization of -histidine single crystals. Hence, it is decided to study
L-histidine crystals
L
L
L
the structural, optical and thermal properties and discussed in suc-
ceeding sections.
Powder X-ray diffraction analyses
needle type crystals have been identified as L-histidine and the
bulk one as
L
-histidine hydrochloride monohydrate (LHHC). The
The grown crystals were also subjected to powder X-ray diffrac-
tion analyses. Thedata have beencollectedat 298 K between 10° and
80° ofdiffractionangleswiththesourcewavelengthof1.5460 Å. The
measured dimensions are 7 ꢁ 6 ꢁ 30 mm3 and 18ꢁ 10ꢁ 20 mm3
for the grown crystals of L-histidine and LHHC respectively.
Anandan
