If I understand your question correctly, you are interested in adding the
itemprop="image" portion? The function
the_post_thumbnail() takes a second argument that allows you to pass in an array of HTML attributes. Thus to create this you could write the following:
'itemprop' => 'image',
'class' => 'alignright size-full wp-image-753',
'alt' => 'image.jpg'
If I am not understanding you correctly, and you are interested in using the new html 5 image tag or something else then you can always query for just the image src like so:
$imageUrl = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'full' );
I hope that this helps!