Hi,
Although there is no single format code which gives the output as you required, but you may try the following combination to get your date time format:-
declare @starttime as datetime
set @starttime = '12/4/2011 12:53:40 PM'
select convert(varchar, @starttime, 101) +' '+ convert(varchar, @starttime, 108)+ ' '+ right(convert(varchar, @starttime, 109),2)
-- Output
12/04/2011 12:53:40 PM