Fix Python – Python pandas insert list into a cell

I have a list ‘abc’ and a dataframe ‘df’:
abc = [‘foo’, ‘bar’]
df =
A B
0 12 NaN
1 23 NaN

I want to insert the list into cell 1B, so I want this result:
A B
0 12 NaN
1 23 [‘foo’, ‘bar’]

Ho can I do that?
1) If I use this:
df.ix[1,’B’] = abc

I get the following error message:
ValueError: Must have equal len keys and value when ….