I'm given the structures of molecules that are potentially liquid crystals for use in LCDs and asked to choose the most appropriate molecules.
I know that in order for the molecule to function in LCDs, they need to be polar.
From the image above, I already know that molecule 1 can be used as a liquid crystal. From the options I'm given in the question, I know that the answer is molecule 1 with molecule 2 OR 3. However, it seems like a toss-up between molecules 2 and 3 to me.
I think that the high electronegativity of the Cl atom on molecule 2 makes the molecule polar. However, just like molecule 1, molecule 3 has the carbon-nitrogen triple bond which gives molecule 1 it's polarity. Would molecule 2 be chosen over molecule 3 because it has a similar structure/size as molecule 1?