This document provides an overview of liquid crystal phases. It discusses the history of liquid crystals, introducing key figures like Reinitzer and Lehmann. It describes that liquid crystals have properties of both liquids and crystals, with varying degrees of positional and orientational order. There are two main types of liquid crystals - lyotropic, which form when amphiphiles are dissolved in solvents, and thermotropic, which form when compounds are heated or cooled. Common liquid crystal phases include nematic, smectic, and cholesteric. Order parameters are used to quantify the amount of order in different phases. The document concludes by covering some applications of liquid crystals in pharmaceuticals, cosmetics, and for solubility enhancement.

1. SEMINAR ON
LIQUID CRYSTAL PHASE
Prepared By: Under the guidance of:
Ansari raees ahmad, Assit.prof:A.D.Savkare sir,
M pharm sem-l
Roll No.22
DEPARTMEANT OF PHARMACEUTICS
M.V.P. SAMAJ’S COLLEGE OF PHARMACY,NASHIK
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2. CONTENTS:
 HISTORY.
 INTRODUCTION TO LCs(LIQUID CRYSTAL).
 LIQUID CRYSTAL PHASES.
 LIQUID CRYSTAL PHASES CHARACTERIZATION.
 LYOTROPIC LCs.
 THERMOTROPIC LCs.
 NEMATIC,SMECTIC,CHOLESTERIC PHASE.
 ORDER PARAMETER.
 APPLICATION OF LCs.
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3. HISTORY OF LIQUID CRYSTAL
1888, Austrian Botanist Freidrich
Reinitzer discovers liquid crystals.
Otto Lehmann was expert in crystal
optics who studied and said cloudy
liquid has new state of matter ‘liquid
crystal’
1897,German scientist Karl Braun
invents the cathode ray tube (CRT).
Till 1890 all the liquid crystalline substances that had been
investigated naturally occurring and it was then that the first synthetic
liquid crystal, p-azoxyanisole,was produced by Gatterman and
Ritschke.
e.g:Isooctane,ammonium thiocyanate,sodium decanoate.
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4. WHAT ARE LIQUID CRYSTALS?
 substance is in two quite different state of matter at the same time.
 The two most common states of matters are the isotropic liquid
phase and the crystalline solid phase.
 liquid crystalline phases represent intermediate states and are also
called mesophases.
 In an isotropic liquid the molecules have neither positional nor
orientational order, they are distributed randomly.
 In a crystal, the molecules or atoms have both orientational and
three-dimensional positional order over a long range.
Fig:Liquid
crystal model
isotropic
&anisotropic.
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5. LIQUID CRYSTAL IS IT SOLID OR LIQUID?
 The amount of heat required to cause phase transition is called as
latent heat
 Heat of transition is useful to measure how different the the two
phases are.
 In case of cholesteryl myristate the latent heat of solid to liquid
crystal is 65 calories/gm.
 While the latent heat for liquid crystal to liquid transition is 07
calories/gm.
 Smallest the latent heat of liquid crystal to liquid phase transition
then liquid crystals are more similar to liquid than solid.
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6. LIQUID CRYSTALLINE PHASES
Mesophase: A phase lying between solid and liquid.formed by
changing amount of order in sample.
Liquid crystal:fluid having properties associated to both crystal and
liquid.
Lyotropic: The liquid crystalline state may result when molecules
are mixed with certain solvents or solids.
Thermotropic : The liquid crystalline state may result when the
compound is heated.
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7. LIQUID CRYSTAL PHASE CHARACTERIZATION
Following character describe the crystalline structure.
1)Positional order:the extent to which an average molecule or group of
molecules shows translational symmetry (as crystalline material shows).
2)Orientational order: represents a measure of the tendency of the molecules
to align along the director on a long-range basis.
3)Bond Orientational Order :describes a line joining the centers of nearest-
neighbor molecules without requiring a regular spacing along that line.
Positional order + Orientational order= crystal phase
Varying Positional order + Orientational order=LC phase
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8. LYOTROPIC LIQUID CRYSTAL
Figure: Phospholipid (lecithin),
present in cell membranes, in a
bilayer Lyotropic liquid crystal
arrangement
Figure:Sodium dodecylsulfate
(soap) forming micelles
LLCs are two-component systems where an amphiphile is dissolved
in a solvent.Phase transition depend on concentration.
Thus, lyotropic mesophases are concentration and solvent dependent.
The amphiphilic compounds are characterised by two distinct
moieties a hydrophilic polar “head” and a hydrophobic “tail”.
Examples of these kinds of molecules are as follows:
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9. THERMOTROPIC LIQUID CRYSTAL
 In case of thermotropic LCs solid changes to liquid crystalline phase
above the melting point.
 If transitions between the phases are given by temperature, they are
called thermotropic.
 While thermotropics are presently mostly used for technical
applications.
 The essential requirement for a molecule to be a thermotropic LC is a
structure consisting of a central rigid core (often aromatic) and a flexible
peripheral moiety (generally aliphatic groups).
 This structural requirement leads to two general classes of LCs:
1. Calamitic LCs, and
2. Discotic LCs 9

10. THERMOTROPIC LIQUID CRYSTAL
Calamitic or rod-like LCs :Are those
compounds that possess an elongated
shape, responsible for the form
anisotropy of the molecular structure,
as the result of the molecular length (l)
being significantly greater than the
molecular breadth(b)
Discotic LCs: the molecular diameter
(d) is much greater than the disc
thickness (t), imparting the form
anisotropy to the molecular structure.
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11. NEMATIC PHASE
 Nematic(Greek) means thread like structure.
 It is thread like structure when seen under
microscope.
 It is only crystal phase with no long transitional
order.
 The nematic liquid crystal phase is
characterized by molecules that have no
positional order but tend to point in the same
direction (along the director).
 In the diagram, notice that the molecules point
vertically but are arranged with no particular
order.
 Molecules in this phase are long and rod like.
 They are free to move in space. 11

12. SMECTIC PHASE
 Smectic is Greek word means soap like.
 smectic phase show translational order which is
not shown by nematic phase.
 These phases can be seen as crystalline in one
direction and liquid-like in other two directions.
 Smectic phase(Liquid Crystal) retain a two
dimensional order.
 In the smectic phase the layer of the molecules
are quite flexible.
 It extends all over the specimen and when
examined under polarized light it gives a fan-
like appearance.
 It is unaffected by magnetic and electric fields.
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13. CHIRAL LIQUID CRYSTAL-CHOLESTERIC
 Chiral molecules(molecules lacking a center of symmetry) can
assume a cholesteric phase,also called as a chiral nematic phase.
 Important characteristic of the cholesteric mesophase is the pitch.
 The pitch, p, is defined as the distance it takes for the molecule to
complete one turn is called pitch.
 An application of a class of chiral nematic liquid crystals which are
less temperature sensitive is to create materials such as, clothing,
inks, dolls and paints.
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14. ORDER PARAMETER
 To quantify just how much order is present in
material, an order parameter (S)is defined.
 Where, theta is the angle between the director and
the long axis of each molecule.
 The brackets denote an average over all of the
molecules in the sample.
 In an isotropic liquid, the average of the cosine
terms is zero, and therefore the order parameter
is equal to zero.
 For a perfect crystal, the order parameter evaluates
to one. Typical values for the order parameter of
a liquid crystal range between 0.3 and 0.9 .
Graph :Values for
the order parameter
of a liquid crystal.
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15. APPLICATION OF LIQUID CRYSTALS
Application in pharma:Appox. 5%of all organic molecule exist as
thermotropic LCs.
 Pharmaceutical compounds increasingly characterised by their
lyotropic liquid crystalline structure.
 LLCs based delivery system such as creams,ointment, liposome's,
gels,transdermal patches,have been used in pharmaceutical.
LCs in cosmetics:LCs used for decorative purposes in cosmetics.
 Cholesteric liquids are suitable due to their iridescent colour
effect,and find application as colouring for nails,eyeshadows,and
lipsticks.
 The structure of these thermotropic LCs changes with body
temperature,resulting in required colour effect.
 In recent time these thermotropic cholesteric LCs have been included
in body care cosmetics. 15

16. Pharma drugs as LCs:
small molecular pharmaceutical active compounds :
 Nafoxidine hydrochloride this is cationic drug has amphiphilic
properties and gives rise thermotropic (smectic type) and lyotropic
liquid crystalline structures.
 Palmitolyl propranolol hydrochloride is an amphiphilic derivative
of the beta-blocker propranolol hydrochloride which forms smectic
type liquid crystalline phase. It has been administered as liquid
crystalline dispersion for cardiac problems.
Itraconazole hydrochloride is an antifungal drug which forms chiral
nematic phases.
 Some of the other examples of small molecular pharmaceuticals
which can form LCs are arsphenamine, fenoprofen sodium,
fenoprofen calcium, penbutolol sulphate, nafcillin, methotrexate,
folic acid and tobramycin.
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17.  Large molecular pharmaceutical active compounds :
cyclosporine, calcitonin, amylin, nafarelin, detirelix and leuprolide.
 the pharmaceutical excipients such as hydroxypropylcellulose,
ethyl cellulose and cellulose acetate have also displayed LC phases.
 Examples of naturally occurring LCs are DNA, cholesterol, silk
worm,spider silk,bacterial plasmid and the biological membranes.
 Smectic nanoparticles: Colloidal smectic nanoparticles are
emerging as a carrier system for lipophilic drugs due to their liquid
crystalline nature. e.g:cholesteryl myristate.
 Colloidal smectic nanoparticles are suitable models to study the
crystallization behavior of pharmaceuticals and determining the
influence of various parameters for the development of smectic
nanoparticles which are resistant to crystallization upon storage.
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18. LCs for solubility enhancement :
 Liquid crystalline state of lipids has been used as a model to
mimic the biological systems. In various foods, pharmaceutical
and biotechnical applications.
 the liquid crystalline phases formed by surfactants in aqueous
medium represent useful host systems for drugs, amino acids,
peptides, proteins and vitamins.
 Various biologically active food additives are soluble in neither
aqueous nor oil phase and require environmental protection
against hydrolysis or oxidation.
 Lyotropic liquid crystals meet these requirements mainly due to
their high solubilization capacities for hydrophilic, lipophilic and
amphiphilic guest molecules.
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19. DERMALAPPLICATION
 Drug molecules and pharmaceutical excipients with amphiphilic
character can form lyotropic mesophases.
 particularly for surfactants, which are commonly used as emulsifiers
in dermal formulations and associate to form micelles after
dissolving in a solvent.
 With increasing concentration the probability of interaction between
the micelles increases and thus liquid crystals form.
 Liquid crystalline formulations have been used in cosmetics and
pharmaceutical controlled release dosage forms.
 These formulations achieve enhanced penetration of biologically
active materials (e.g., vitamin A) into the skin. The delivery systems
consist of cholesteric liquid crystals wherein the active material is
retained within the lamellar molecular structure (i.e. between the
molecular sheets) of the cholesteric liquid crystal. 19

20.  Medicinal Uses:Cholesteric LCs mixture
also been suggested to measure body skin
temprature.
 Help in location of inflamation the warmer
area will outline by colour pattern.
 In gynecology LCs used to locate placenta
thus avoiding need of x-ray.
 Lycotropic liquids are also incorporated in
special dermatological formulation that
exhibit hydrating properties.
 Most of LCs are used as excipient to protect
sensetive substances(vitamins,antioxidants ,
oil,etc)
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22. REFERENCES:
 Prajakta P. Gaikwad, Maya T. Desai ,Liquid Crystalline Phase &
its Pharma Applications,International Journal of Pharma Research
& Review, Dec 2013; 40-52.
 Jain Hitesh et al. IRJP Liquid crystals accelerating in drug
absorption from topical formulation,2011;86-89.
 http://pli.cwru.edu/tutorial/enhanced/files/lc/phase.
 Christel C. Mueller-Goymann: Drug Delivery: Liquid Crystals in;
Encyclopedia of pharmaceutical technology,third edition, edited
by James Swarbrick ,USA;vol.2 ,2007:1115-30.
 Martin's physical pharmacy and pharmaceutical sciences:
physical,chemical and biopharmaceutical principles in the
pharmaceutical sciences.6th ed./ editor. Patrick J. Sinko; assistant
editor.Yashveer Singh.Page no:36.
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