I generate articles with the help of VIEWS at front-page. But I want that the second article has a different look. So I want to add div-Tags and additional css-classes to that second article. I have tried to do this with a boolean field but the teaser does not have the possibility to check whether boolean field is true or false. Any idea how I can realize it??
One approach to do this is to use multiple views. One that displays only one node and a second one that displays the others, with an offset of one. Then it's easy to configure those views to use different view modes then. You can do that using Page Manager/Panels, Views attachments or possibly also core blocks.
One thing that can be a challenge to figure out is paging, depends on what you expect to see on the second page exactly. If you have paging, then a different approach might be necessary, for example by changing the view mode of the first view through code, through a preprocess hook or so.